electron/patches/chromium/mas_avoid_private_macos_api_usage.patch.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Samuel Attard <samuel.r.attard@gmail.com>
Date: Thu, 20 Sep 2018 17:48:49 -0700
Subject: mas: avoid private macOS API usage

* Use the stub killring file when building blink
* Remove usage of the following private APIs
  * abort_report_np
  * pthread_fchdir_np
  * pthread_chdir_np
  * SetApplicationIsDaemon
  * _LSSetApplicationLaunchServicesServerConnectionStatus
  * AreDeviceAndUserJoinedToDomain
  * _CFIsObjC
  * AudioDeviceDuck
  * NSNextStepFrame
  * NSThemeFrame
  * NSTextInputReplacementRangeAttributeName
* NSAccessibilityRemoteUIElement is unnecessary for Electron's use-case. We use it
for progressive web apps (where the AXTree is in the browser process, but macOS
needs to think it's coming from the PWA process). I think it can just be chopped
out -- if there are any side-effects, we should be able to work around them.
* CAContext removal
  * For apps that spend a lot of time watching video (especially fullscreen video),
    the power/battery usage will likely increase 1.5x to 2x. For something that is,
    e.g, scrolling, it'll be smaller, more like 1.15x or 1.25x.

    In terms of performance, the impact will likely be fairly small -- any app that
    could hit 60fps before will likely still be able to hit 60fps. There may even be
    cases where performance improves when disabling remote CoreAnimation (remote
    CoreAnimation is really only about battery usage).
* CTFontDescriptorIsSystemUIFont is a private API, we're using an
_interesting_ technique in the MAS build to determine if the font is a
system font by checking if it's kCTFontPriorityAttribute is set to
system priority.

diff --git a/base/BUILD.gn b/base/BUILD.gn
index d62d3c4a82579a5b308f28b941db0cc8e48d0e37..865519a1179d573b0a99ec32d9dcd81f04c0f9d6 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1045,6 +1045,7 @@ component("base") {
     "//build:ios_buildflags",
     "//build/config/compiler:compiler_buildflags",
     "//third_party/modp_b64",
+    "//electron/build/config:generate_mas_config",
   ]
   if (!is_nacl) {
     # Used by metrics/crc32, except on NaCl builds.
diff --git a/base/enterprise_util_mac.mm b/base/enterprise_util_mac.mm
index 4bf9a3c27e05c6635b2beb8e880b5b43dbed61b5..f328fbb49c45991f44a9c75325491d0873746b61 100644
--- a/base/enterprise_util_mac.mm
+++ b/base/enterprise_util_mac.mm
@@ -16,6 +16,7 @@
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
+#include "electron/mas.h"
 
 namespace base {
 
@@ -116,6 +117,14 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
     DeviceUserDomainJoinState state{.device_joined = false,
                                     .user_joined = false};
 
+#if IS_MAS_BUILD()
+    return state;
+  }();
+
+  return state;
+}
+#else
+
     @autoreleasepool {
       ODSession* session = [ODSession defaultSession];
       if (session == nil) {
@@ -219,5 +228,6 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
 
   return state;
 }
+#endif
 
 }  // namespace base
diff --git a/base/process/launch_mac.cc b/base/process/launch_mac.cc
index 29e6d750c5c688f1673a8495156a4b7bcd0ddb44..45a3f6e74221be7498f0ebb8133abbbd4dea10ed 100644
--- a/base/process/launch_mac.cc
+++ b/base/process/launch_mac.cc
@@ -21,6 +21,10 @@
 #include "base/threading/scoped_blocking_call.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/trace_event/base_tracing.h"
+#include "electron/mas.h"
+#if IS_MAS_BUILD()
+#include <sys/syscall.h>
+#endif
 
 #if BUILDFLAG(IS_MAC)
 #include "base/apple/mach_port_rendezvous_mac.h"
@@ -29,9 +33,11 @@
 extern "C" {
 // Changes the current thread's directory to a path or directory file
 // descriptor.
+#if !IS_MAS_BUILD()
 int pthread_chdir_np(const char* dir);
 
 int pthread_fchdir_np(int fd);
+#endif
 
 int responsibility_spawnattrs_setdisclaim(posix_spawnattr_t attrs,
                                           int disclaim);
@@ -108,13 +114,27 @@ class PosixSpawnFileActions {
 
 #if !BUILDFLAG(IS_MAC)
 int ChangeCurrentThreadDirectory(const char* path) {
+#if IS_MAS_BUILD()
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return syscall(SYS___pthread_chdir, path);
+  #pragma clang diagnostic pop
+#else
   return pthread_chdir_np(path);
+#endif
 }
 
 // The recommended way to unset a per-thread cwd is to set a new value to an
 // invalid file descriptor, per libpthread-218.1.3/private/private.h.
 int ResetCurrentThreadDirectory() {
+#if IS_MAS_BUILD()
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return syscall(SYS___pthread_fchdir, -1);
+  #pragma clang diagnostic pop
+#else
   return pthread_fchdir_np(-1);
+#endif
 }
 #endif
 
@@ -238,7 +258,7 @@ Process LaunchProcess(const std::vector<std::string>& argv,
     file_actions.Inherit(STDERR_FILENO);
   }
 
-#if BUILDFLAG(IS_MAC)
+#if 0
   if (options.disclaim_responsibility) {
     DPSXCHECK(responsibility_spawnattrs_setdisclaim(attr.get(), 1));
   }
diff --git a/base/process/process_info_mac.mm b/base/process/process_info_mac.mm
index e12c1d078147d956a1d9b1bc498c1b1d6fe7b974..233362259dc4e728ed37435e650417647b45a6af 100644
--- a/base/process/process_info_mac.mm
+++ b/base/process/process_info_mac.mm
@@ -4,15 +4,20 @@
 
 #include "base/process/process_info.h"
 
+#include "electron/mas.h"
+
 #import <AppKit/AppKit.h>
 #include <unistd.h>
 
+#if !IS_MAS_BUILD()
 extern "C" {
 pid_t responsibility_get_pid_responsible_for_pid(pid_t);
 }
+#endif
 
 namespace {
 
+#if !IS_MAS_BUILD()
 bool AppContainsBluetoothUsageDescription(NSRunningApplication* app) {
   NSURL* bundle_url = app.bundleURL;
   if (!bundle_url) {
@@ -24,12 +29,14 @@ bool AppContainsBluetoothUsageDescription(NSRunningApplication* app) {
       [bundle objectForInfoDictionaryKey:@"NSBluetoothAlwaysUsageDescription"];
   return bluetooth_entry != nil;
 }
+#endif
 
 }  // namespace
 
 namespace base {
 
 bool DoesResponsibleProcessHaveBluetoothMetadata() {
+#if !IS_MAS_BUILD()
   const pid_t pid = getpid();
   const pid_t responsible_pid = responsibility_get_pid_responsible_for_pid(pid);
   // Returns true directly if this is a self-responsible app(e.g. Chrome opens
@@ -46,6 +53,9 @@ bool DoesResponsibleProcessHaveBluetoothMetadata() {
     return AppContainsBluetoothUsageDescription(app);
   }
   return false;
+#else
+  return true;
+#endif
 }
 
 }  // namespace base
diff --git a/components/os_crypt/sync/BUILD.gn b/components/os_crypt/sync/BUILD.gn
index ff1e356ff696d3830d02644969c36a71fdf32ff6..b39c716c52524b95f2d3417a98e60c0c41147c93 100644
--- a/components/os_crypt/sync/BUILD.gn
+++ b/components/os_crypt/sync/BUILD.gn
@@ -38,6 +38,8 @@ component("sync") {
       "os_crypt_mac.mm",
     ]
     deps += [ "//crypto:mock_apple_keychain" ]
+    deps += ["//electron/build/config:generate_mas_config"]
+
   } else if (is_win) {
     sources += [ "os_crypt_win.cc" ]
     deps += [ "//components/version_info" ]
diff --git a/components/os_crypt/sync/keychain_password_mac.mm b/components/os_crypt/sync/keychain_password_mac.mm
index d87682447b850e4cf9065f0d26d14077acbe467d..a179c9bc02158130f4b15bf8022721f4b53a8303 100644
--- a/components/os_crypt/sync/keychain_password_mac.mm
+++ b/components/os_crypt/sync/keychain_password_mac.mm
@@ -14,6 +14,7 @@
 #include "base/rand_util.h"
 #include "build/branding_buildflags.h"
 #include "crypto/apple_keychain.h"
+#include "electron/mas.h"
 
 using crypto::AppleKeychain;
 
diff --git a/components/remote_cocoa/app_shim/BUILD.gn b/components/remote_cocoa/app_shim/BUILD.gn
index ad40ddbbcb0fcfa070833ea6c0d01432bbb67768..df632da340c132f469f4f35738514763437e67fc 100644
--- a/components/remote_cocoa/app_shim/BUILD.gn
+++ b/components/remote_cocoa/app_shim/BUILD.gn
@@ -75,6 +75,7 @@ component("app_shim") {
     "//components/crash/core/common",
     "//components/remote_cocoa/common:mojo",
     "//components/system_media_controls",
+    "//electron/build/config:generate_mas_config",
     "//mojo/public/cpp/bindings",
     "//net",
     "//ui/accelerated_widget_mac",
diff --git a/components/remote_cocoa/app_shim/application_bridge.mm b/components/remote_cocoa/app_shim/application_bridge.mm
index e9f4e5131238b9fb5f1b4b3e90a0cb84a7fc15b4..8b5f4cae3123ac5480ad73f0c873fca0d62f7c9f 100644
--- a/components/remote_cocoa/app_shim/application_bridge.mm
+++ b/components/remote_cocoa/app_shim/application_bridge.mm
@@ -12,6 +12,7 @@
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_host_helper.h"
 #include "components/system_media_controls/mac/remote_cocoa/system_media_controls_bridge.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "mojo/public/cpp/bindings/self_owned_receiver.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
@@ -51,6 +52,7 @@
 
   // NativeWidgetNSWindowHostHelper:
   id GetNativeViewAccessible() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       base::ProcessId browser_pid = base::kNullProcessId;
       std::vector<uint8_t> element_token;
@@ -61,6 +63,9 @@ id GetNativeViewAccessible() override {
           ui::RemoteAccessibility::GetRemoteElementFromToken(element_token);
     }
     return remote_accessibility_element_;
+#else
+    return nil;
+#endif
   }
   void DispatchKeyEvent(ui::KeyEvent* event) override {
     bool event_handled = false;
@@ -99,7 +104,9 @@ void GetWordAt(const gfx::Point& location_in_content,
   mojo::AssociatedRemote<mojom::TextInputHost> text_input_host_remote_;
 
   std::unique_ptr<NativeWidgetNSWindowBridge> bridge_;
+#if !IS_MAS_BUILD()
   NSAccessibilityRemoteUIElement* __strong remote_accessibility_element_;
+#endif
 };
 
 }  // namespace
diff --git a/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm b/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
index 92646b4978457724d46eb526d6f34cd308562f0b..c3e669ed8fb0682f7f973bb1c69d069bd6a3aa0c 100644
--- a/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
+++ b/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
@@ -9,7 +9,9 @@
 #include "base/mac/mac_util.h"
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 namespace {
 // Workaround for https://crbug.com/1369643
 const double kThinControllerHeight = 0.5;
@@ -100,12 +102,15 @@ - (void)maybeShowTrafficLights {
 
 @end
 
+#endif  // MAS_BUILD
+
 @implementation BrowserNativeWidgetWindow
 
 @synthesize thinTitlebarViewController = _thinTitlebarViewController;
 
 // NSWindow (PrivateAPI) overrides.
 
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   // - NSThemeFrame and its subclasses will be nil if it's missing at runtime.
   if ([BrowserWindowFrame class])
@@ -164,6 +169,8 @@ - (BOOL)_usesCustomDrawing {
   return NO;
 }
 
+#endif  // MAS_BUILD
+
 // Handle "Move focus to the window toolbar" configured in System Preferences ->
 // Keyboard -> Shortcuts -> Keyboard. Usually Ctrl+F5. The argument (|unknown|)
 // tends to just be nil.
@@ -174,8 +181,8 @@ - (void)_handleFocusToolbarHotKey:(id)unknown {
 }
 
 - (void)setAlwaysShowTrafficLights:(BOOL)alwaysShow {
-  [base::apple::ObjCCastStrict<BrowserWindowFrame>(self.contentView.superview)
-      setAlwaysShowTrafficLights:alwaysShow];
+  // [base::apple::ObjCCastStrict<BrowserWindowFrame>(self.contentView.superview)
+  //    setAlwaysShowTrafficLights:alwaysShow];
 }
 
 @end
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm b/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
index 3a815ebf505bd95fa7f6b61ba433d98fbfe20225..149de0175c2ec0e41e3ba40caad7019ca87386d6 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
@@ -4,6 +4,10 @@
 
 #import "components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.h"
 
+#include "electron/mas.h"
+
+#if !IS_MAS_BUILD()
+
 @interface NSWindow (PrivateAPI)
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle;
 @end
@@ -18,8 +22,12 @@ - (CGFloat)_titlebarHeight {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacFramelessNSWindow
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   if ([NativeWidgetMacFramelessNSWindowFrame class]) {
     return [NativeWidgetMacFramelessNSWindowFrame class];
@@ -27,4 +35,6 @@ + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   return [super frameViewClassForStyleMask:windowStyle];
 }
 
+#endif  // MAS_BUILD
+
 @end
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
index 127a2829fafa04bfbab0b883304dfb815d7e1c22..61d7946e52862f3586b1e098d7d44a125656de81 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
@@ -9,6 +9,7 @@
 
 #include "base/apple/foundation_util.h"
 #include "components/remote_cocoa/app_shim/remote_cocoa_app_shim_export.h"
+#include "electron/mas.h"
 #import "ui/base/cocoa/command_dispatcher.h"
 
 namespace remote_cocoa {
@@ -17,6 +18,7 @@ class NativeWidgetNSWindowBridge;
 
 @protocol WindowTouchBarDelegate;
 
+#if !IS_MAS_BUILD()
 // Weak lets Chrome launch even if a future macOS doesn't have the below classes
 WEAK_IMPORT_ATTRIBUTE
 @interface NSNextStepFrame : NSView
@@ -33,6 +35,7 @@ REMOTE_COCOA_APP_SHIM_EXPORT
 REMOTE_COCOA_APP_SHIM_EXPORT
 @interface NativeWidgetMacNSWindowTitledFrame : NSThemeFrame
 @end
+#endif
 
 // The NSWindow used by BridgedNativeWidget. Provides hooks into AppKit that
 // can only be accomplished by overriding methods.
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
index fd680a4d99d14ce4203e696dd262e1b642394e55..1765e6f44b2d80338f6c20ec65921685c5dc98d5 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
@@ -26,6 +26,7 @@
 #import "components/remote_cocoa/app_shim/views_nswindow_delegate.h"
 #import "components/remote_cocoa/app_shim/window_touch_bar_delegate.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 #include "ui/accessibility/platform/ax_platform_node.h"
 #import "ui/base/cocoa/user_interface_item_command_handler.h"
 #import "ui/base/cocoa/window_size_constants.h"
@@ -113,14 +114,18 @@ void OrderChildWindow(NSWindow* child_window,
 
 }  // namespace
 
+#if !IS_MAS_BUILD()
 @interface NSNextStepFrame (Private)
 - (instancetype)initWithFrame:(NSRect)frame
                     styleMask:(NSUInteger)styleMask
                         owner:(id)owner;
 @end
+#endif
 
 @interface NSWindow (Private)
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle;
+#endif
 - (BOOL)hasKeyAppearance;
 - (long long)_resizeDirectionForMouseLocation:(CGPoint)location;
 - (BOOL)_isConsideredOpenForPersistentState;
@@ -170,6 +175,8 @@ - (void)cr_mouseDownOnFrameView:(NSEvent*)event {
 }
 @end
 
+#if !IS_MAS_BUILD()
+
 @implementation NativeWidgetMacNSWindowTitledFrame
 - (void)mouseDown:(NSEvent*)event {
   if (self.window.isMovable)
@@ -197,6 +204,8 @@ - (BOOL)usesCustomDrawing {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacNSWindow {
  @private
   CommandDispatcher* __strong _commandDispatcher;
@@ -394,6 +403,8 @@ - (NSAccessibilityRole)accessibilityRole {
 
 // NSWindow overrides.
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   if (windowStyle & NSWindowStyleMaskTitled) {
     if (Class customFrame = [NativeWidgetMacNSWindowTitledFrame class])
@@ -405,6 +416,8 @@ + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   return [super frameViewClassForStyleMask:windowStyle];
 }
 
+#endif
+
 - (BOOL)_isTitleHidden {
   bool shouldShowWindowTitle = YES;
   if (_bridge)
diff --git a/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm b/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
index 0b964e176e59e77a0743e2d347aa185bc7c80bc5..49a60b9aa0597c3397906303b73a4c1650cc60ce 100644
--- a/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
+++ b/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
@@ -42,6 +42,7 @@
 #import "components/remote_cocoa/app_shim/views_nswindow_delegate.h"
 #import "components/remote_cocoa/app_shim/window_move_loop.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/self_owned_receiver.h"
 #include "net/cert/x509_util_apple.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
@@ -681,10 +682,12 @@ NSUInteger CountBridgedWindows(NSArray* child_windows) {
   // this should be treated as an error and caught early.
   CHECK(bridged_view_);
 
+#if !IS_MAS_BUILD()
   // Send the accessibility tokens for the NSView now that it exists.
   host_->SetRemoteAccessibilityTokens(
       ui::RemoteAccessibility::GetTokenForLocalElement(window_),
       ui::RemoteAccessibility::GetTokenForLocalElement(bridged_view_));
+#endif
 
   // Beware: This view was briefly removed (in favor of a bare CALayer) in
   // https://crrev.com/c/1236675. The ordering of unassociated layers relative
diff --git a/components/viz/service/BUILD.gn b/components/viz/service/BUILD.gn
index 4704b26c54e7bd449a6e57de43b7c4b0875732c9..e3b4148376f5a93f053b88e179f51cb642d896ed 100644
--- a/components/viz/service/BUILD.gn
+++ b/components/viz/service/BUILD.gn
@@ -385,6 +385,7 @@ viz_component("service") {
         "frame_sinks/external_begin_frame_source_mac.h",
       ]
     }
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_ios) {
@@ -697,6 +698,7 @@ viz_source_set("unit_tests") {
       "display_embedder/software_output_device_mac_unittest.mm",
     ]
     frameworks = [ "IOSurface.framework" ]
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_win) {
diff --git a/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm b/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
index dbf334caa3a6d10017b69ad76802e389a011436b..da828823e8195cc9e497866363c9af93dcd4ec3f 100644
--- a/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
+++ b/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
@@ -15,6 +15,7 @@
 #include "content/common/web_contents_ns_view_bridge.mojom.h"
 #include "content/public/browser/remote_cocoa.h"
 #include "content/public/browser/render_widget_host_view_mac_delegate.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_receiver.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "mojo/public/cpp/bindings/pending_associated_receiver.h"
@@ -63,7 +64,9 @@ explicit RenderWidgetHostNSViewBridgeOwner(
       const RenderWidgetHostNSViewBridgeOwner&) = delete;
 
  private:
+#if !IS_MAS_BUILD()
   NSAccessibilityRemoteUIElement* __strong remote_accessibility_element_;
+#endif
   void OnMojoDisconnect() { delete this; }
 
   std::unique_ptr<blink::WebCoalescedInputEvent> TranslateEvent(
@@ -75,6 +78,7 @@ explicit RenderWidgetHostNSViewBridgeOwner(
   }
 
   id GetAccessibilityElement() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       base::ProcessId browser_pid = base::kNullProcessId;
       std::vector<uint8_t> element_token;
@@ -85,6 +89,9 @@ id GetAccessibilityElement() override {
           ui::RemoteAccessibility::GetRemoteElementFromToken(element_token);
     }
     return remote_accessibility_element_;
+#else
+    return nil;
+#endif
   }
 
   // RenderWidgetHostNSViewHostHelper implementation.
@@ -103,8 +110,10 @@ id GetFocusedBrowserAccessibilityElement() override {
     return [bridgedContentView accessibilityFocusedUIElement];
   }
   void SetAccessibilityWindow(NSWindow* window) override {
+#if !IS_MAS_BUILD()
     host_->SetRemoteAccessibilityWindowToken(
         ui::RemoteAccessibility::GetTokenForLocalElement(window));
+#endif
   }
 
   void ForwardKeyboardEvent(const input::NativeWebKeyboardEvent& key_event,
diff --git a/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm b/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
index 4017ee032569466f5311e5c9612c82c086eab935..f2499bc084312a09b2324567d270fc1b899e7617 100644
--- a/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
+++ b/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
@@ -35,6 +35,7 @@
 #include "content/public/browser/browser_accessibility_state.h"
 #import "content/public/browser/render_widget_host_view_mac_delegate.h"
 #include "content/public/common/content_features.h"
+#include "electron/mas.h"
 #include "skia/ext/skia_utils_mac.h"
 #include "third_party/blink/public/common/features.h"
 #include "third_party/blink/public/mojom/input/input_handler.mojom.h"
@@ -2136,15 +2137,21 @@ - (NSAccessibilityRole)accessibilityRole {
 // Since this implementation doesn't have to wait any IPC calls, this doesn't
 // make any key-typing jank. --hbono 7/23/09
 //
+#if !IS_MAS_BUILD()
 extern "C" {
 extern NSString* NSTextInputReplacementRangeAttributeName;
 }
+#endif
 
 - (NSArray*)validAttributesForMarkedText {
   // This code is just copied from WebKit except renaming variables.
   static NSArray* const kAttributes = @[
     NSUnderlineStyleAttributeName, NSUnderlineColorAttributeName,
+#if !IS_MAS_BUILD()
     NSMarkedClauseSegmentAttributeName, NSTextInputReplacementRangeAttributeName
+#else
+    NSMarkedClauseSegmentAttributeName
+#endif
   ];
   return kAttributes;
 }
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index f999eb6aeb11b59c6231b8f80d9e0d586b341171..679ee6731e685a9844bb6461d664f8e5b823e258 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -341,6 +341,7 @@ source_set("browser") {
     "//ui/webui/resources",
     "//v8",
     "//v8:v8_version",
+    "//electron/build/config:generate_mas_config",
   ]
 
   public_deps = [
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 1b923f0e0dc6d7dc9e67d278b8da00b35745241e..6f7ee79df9b9e3026663e2a4637007de5b5da902 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -24,6 +24,7 @@
 #include "content/browser/renderer_host/text_input_manager.h"
 #include "content/common/content_export.h"
 #include "content/common/render_widget_host_ns_view.mojom.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_receiver.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "third_party/blink/public/mojom/webshare/webshare.mojom.h"
@@ -54,7 +55,9 @@ class CursorManager;
 
 @protocol RenderWidgetHostViewMacDelegate;
 
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class RenderWidgetHostViewCocoa;
 
 namespace content {
@@ -692,9 +695,11 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   // EnsureSurfaceSynchronizedForWebTest().
   uint32_t latest_capture_sequence_number_ = 0u;
 
+#if !IS_MAS_BUILD()
   // Remote accessibility objects corresponding to the NSWindow that this is
   // displayed to the user in.
   NSAccessibilityRemoteUIElement* __strong remote_window_accessible_;
+#endif
 
   // Used to force the NSApplication's focused accessibility element to be the
   // content::BrowserAccessibilityCocoa accessibility tree when the NSView for
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 27f481c6a31cdd59684eb38ea8b2ffdcb5849ddf..88a6090a49da6071fded348a901c7c62b647b503 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -50,6 +50,7 @@
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_visibility_state.h"
+#include "electron/mas.h"
 #include "media/base/media_switches.h"
 #include "skia/ext/platform_canvas.h"
 #include "skia/ext/skia_utils_mac.h"
@@ -274,8 +275,10 @@
 void RenderWidgetHostViewMac::MigrateNSViewBridge(
     remote_cocoa::mojom::Application* remote_cocoa_application,
     uint64_t parent_ns_view_id) {
+#if !IS_MAS_BUILD()
   // Destroy the previous remote accessibility element.
   remote_window_accessible_ = nil;
+#endif
 
   // Reset `ns_view_` before resetting `remote_ns_view_` to avoid dangling
   // pointers. `ns_view_` gets reinitialized later in this method.
@@ -1632,10 +1635,12 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 
 gfx::NativeViewAccessible
 RenderWidgetHostViewMac::AccessibilityGetNativeViewAccessibleForWindow() {
+#if !IS_MAS_BUILD()
   if (remote_window_accessible_) {
     return gfx::NativeViewAccessible(
         (id<NSAccessibility>)remote_window_accessible_);
   }
+#endif
   return gfx::NativeViewAccessible([GetInProcessNSView() window]);
 }
 
@@ -1687,9 +1692,11 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 }
 
 void RenderWidgetHostViewMac::SetAccessibilityWindow(NSWindow* window) {
+#if !IS_MAS_BUILD()
   // When running in-process, just use the NSView's NSWindow as its own
   // accessibility element.
   remote_window_accessible_ = nil;
+#endif
 }
 
 bool RenderWidgetHostViewMac::SyncIsWidgetForMainFrame(
@@ -2216,20 +2223,26 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 void RenderWidgetHostViewMac::GetRenderWidgetAccessibilityToken(
     GetRenderWidgetAccessibilityTokenCallback callback) {
   base::ProcessId pid = getpid();
+#if !IS_MAS_BUILD()
   id element_id = GetNativeViewAccessible().Get();
   std::vector<uint8_t> token =
       ui::RemoteAccessibility::GetTokenForLocalElement(element_id);
   std::move(callback).Run(pid, token);
+#else
+  std::move(callback).Run(pid, std::vector<uint8_t>());
+#endif
 }
 
 void RenderWidgetHostViewMac::SetRemoteAccessibilityWindowToken(
     const std::vector<uint8_t>& window_token) {
+#if !IS_MAS_BUILD()
   if (window_token.empty()) {
     remote_window_accessible_ = nil;
   } else {
     remote_window_accessible_ =
         ui::RemoteAccessibility::GetRemoteElementFromToken(window_token);
   }
+#endif
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/content/common/BUILD.gn b/content/common/BUILD.gn
index fb23dfd8f90ad3eeb55e4db373ca67f75d8e5ce1..df902b0b01ed4d092070a92fdf77cf69fde475e7 100644
--- a/content/common/BUILD.gn
+++ b/content/common/BUILD.gn
@@ -283,6 +283,7 @@ source_set("common") {
     "//ui/shell_dialogs",
     "//url",
     "//url/ipc:url_ipc",
+    "//electron/build/config:generate_mas_config",
   ]
 
   defines = []
diff --git a/content/renderer/BUILD.gn b/content/renderer/BUILD.gn
index 7424d33cc34ca44b1949260215b2f0a44a2d393e..80e284ca761069e5d544b5a056b13df32d509d00 100644
--- a/content/renderer/BUILD.gn
+++ b/content/renderer/BUILD.gn
@@ -327,6 +327,7 @@ target(link_target_type, "renderer") {
     "//ui/surface",
     "//url",
     "//v8",
+    "//electron/build/config:generate_mas_config",
   ]
   allow_circular_includes_from = []
 
diff --git a/content/renderer/renderer_main_platform_delegate_mac.mm b/content/renderer/renderer_main_platform_delegate_mac.mm
index d4db3b179725cb96bcbd0f73db7d52ef8b7522db..703b0f56a61abac51961bfd918b7349b943900de 100644
--- a/content/renderer/renderer_main_platform_delegate_mac.mm
+++ b/content/renderer/renderer_main_platform_delegate_mac.mm
@@ -7,12 +7,15 @@
 #import <Cocoa/Cocoa.h>
 
 #include "base/check_op.h"
+#include "electron/mas.h"
 #include "sandbox/mac/seatbelt.h"
 #include "sandbox/mac/system_services.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 CGError CGSSetDenyWindowServerConnections(bool);
 }
+#endif
 
 namespace content {
 
@@ -22,6 +25,7 @@
 // verifies there are no existing open connections), and then indicates that
 // Chrome should continue execution without access to launchservicesd.
 void DisableSystemServices() {
+#if !IS_MAS_BUILD()
   // Tell the WindowServer that we don't want to make any future connections.
   // This will return Success as long as there are no open connections, which
   // is what we want.
@@ -30,6 +34,7 @@ void DisableSystemServices() {
 
   sandbox::DisableLaunchServices();
   sandbox::DisableCoreServicesCheckFix();
+#endif
 }
 
 }  // namespace
diff --git a/content/renderer/theme_helper_mac.mm b/content/renderer/theme_helper_mac.mm
index a1068589ad844518038ee7bc15a3de9bc5cba525..1ff781c49f086ec8015c7d3c44567dbec3d00ff8 100644
--- a/content/renderer/theme_helper_mac.mm
+++ b/content/renderer/theme_helper_mac.mm
@@ -7,16 +7,28 @@
 #include <Cocoa/Cocoa.h>
 
 #include "base/strings/sys_string_conversions.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CGFontRenderingGetFontSmoothingDisabled(void);
 }
-
+#endif
 namespace content {
 
 bool IsSubpixelAntialiasingAvailable() {
+#if !IS_MAS_BUILD()
   // See https://trac.webkit.org/changeset/239306/webkit for more info.
   return !CGFontRenderingGetFontSmoothingDisabled();
+#else
+  NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
+  NSString *default_key = @"CGFontRenderingGetFontSmoothingDisabled";
+  // Check that key exists since boolForKey defaults to NO when the
+  // key is missing and this key in fact defaults to YES;
+  if ([defaults objectForKey:default_key] == nil)
+    return false;
+  return ![defaults boolForKey:default_key];
+#endif
 }
 
 }  // namespace content
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 89e50cc56259e90a4ec955bb846c793f2d42cfd6..f64c1614bd8d9782d1c9f9bca20e2f8926893a0f 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -662,6 +662,7 @@ static_library("test_support") {
     "//url",
     "//url/mojom:url_mojom_gurl",
     "//v8",
+    "//electron/build/config:generate_mas_config"
   ]
 
   data_deps = [
@@ -1115,6 +1116,7 @@ static_library("browsertest_support") {
   }
 
   configs += [ "//v8:external_startup_data" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 mojom("content_test_mojo_bindings") {
@@ -1956,6 +1958,7 @@ test("content_browsertests") {
     "//ui/shell_dialogs",
     "//ui/snapshot",
     "//ui/webui:test_support",
+    "//electron/build/config:generate_mas_config"
   ]
 
   if (!(is_chromeos && target_cpu == "arm64" && current_cpu == "arm")) {
@@ -3280,6 +3283,7 @@ test("content_unittests") {
     "//ui/shell_dialogs:shell_dialogs",
     "//ui/webui:test_support",
     "//url",
+    "//electron/build/config:generate_mas_config"
   ]
 
   if (enable_nocompile_tests) {
diff --git a/content/web_test/BUILD.gn b/content/web_test/BUILD.gn
index 8779cf7cbbe2a583fda51867eaebc627f00bd4cd..98da1587fdc8cc8358a69db2b51d39820a0b15f3 100644
--- a/content/web_test/BUILD.gn
+++ b/content/web_test/BUILD.gn
@@ -227,6 +227,7 @@ static_library("web_test_browser") {
     "//ui/gl",
     "//ui/shell_dialogs:shell_dialogs",
     "//url",
+    "//electron/build/config:generate_mas_config"
   ]
 
   # TODO(crbug.com/40139469): Blink test plugin must be migrated from PPAPI.
diff --git a/device/bluetooth/BUILD.gn b/device/bluetooth/BUILD.gn
index e69ef178a08ef322764809e6afeffa20ffc0cd13..d2e182ed0dad5aeecb48e5a39771880bd8fb408b 100644
--- a/device/bluetooth/BUILD.gn
+++ b/device/bluetooth/BUILD.gn
@@ -256,6 +256,7 @@ component("bluetooth") {
       "CoreBluetooth.framework",
       "Foundation.framework",
     ]
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_mac) {
diff --git a/device/bluetooth/bluetooth_adapter_mac.mm b/device/bluetooth/bluetooth_adapter_mac.mm
index 6431af67ab634cf23729b9102c189b2181cfd2cf..22040e1bfb96d810a2d8e62e44e4afbc684c8c06 100644
--- a/device/bluetooth/bluetooth_adapter_mac.mm
+++ b/device/bluetooth/bluetooth_adapter_mac.mm
@@ -38,7 +38,9 @@
 #include "device/bluetooth/bluetooth_discovery_session_outcome.h"
 #include "device/bluetooth/bluetooth_socket_mac.h"
 #include "device/bluetooth/public/cpp/bluetooth_address.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 // Undocumented IOBluetooth Preference API [1]. Used by `blueutil` [2] and
 // `Karabiner` [3] to programmatically control the Bluetooth state. Calling the
@@ -52,6 +54,7 @@
 // [4] https://support.apple.com/kb/PH25091
 void IOBluetoothPreferenceSetControllerPowerState(int state);
 }
+#endif
 
 // A simple helper class that forwards any Bluetooth device connect notification
 // to its wrapped |_adapter|.
@@ -161,8 +164,10 @@ bool IsDeviceSystemPaired(const std::string& device_address) {
     : controller_state_function_(
           base::BindRepeating(&BluetoothAdapterMac::GetHostControllerState,
                               base::Unretained(this))),
+#if !IS_MAS_BUILD()
       power_state_function_(
           base::BindRepeating(IOBluetoothPreferenceSetControllerPowerState)),
+#endif
       device_paired_status_callback_(
           base::BindRepeating(&IsDeviceSystemPaired)) {
 }
@@ -313,8 +318,12 @@ bool IsDeviceSystemPaired(const std::string& device_address) {
 }
 
 bool BluetoothAdapterMac::SetPoweredImpl(bool powered) {
+#if !IS_MAS_BUILD()
   power_state_function_.Run(base::strict_cast<int>(powered));
   return true;
+#else
+  return false;
+#endif
 }
 
 base::WeakPtr<BluetoothLowEnergyAdapterApple>
diff --git a/gpu/ipc/service/BUILD.gn b/gpu/ipc/service/BUILD.gn
index 81d64e16df0139107bc65c7924bdc467fa392657..3098b80c3dba6e4f8150eae3c5796b1e11c5c899 100644
--- a/gpu/ipc/service/BUILD.gn
+++ b/gpu/ipc/service/BUILD.gn
@@ -129,6 +129,7 @@ component("service") {
       "QuartzCore.framework",
     ]
     defines += [ "GL_SILENCE_DEPRECATION" ]
+    deps += ["//electron/build/config:generate_mas_config"]
   }
   if (is_ios) {
     sources += [ "image_transport_surface_ios.mm" ]
diff --git a/gpu/ipc/service/image_transport_surface_overlay_mac.h b/gpu/ipc/service/image_transport_surface_overlay_mac.h
index ae040bbac8755b677dc6e19383a2390df407e5a6..e95ca30f49506c66a37d6d5269929f437005f863 100644
--- a/gpu/ipc/service/image_transport_surface_overlay_mac.h
+++ b/gpu/ipc/service/image_transport_surface_overlay_mac.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
+#include "electron/mas.h"
 #include "gpu/ipc/service/command_buffer_stub.h"
 #include "gpu/ipc/service/image_transport_surface.h"
 #include "ui/gfx/ca_layer_result.h"
@@ -27,7 +28,9 @@
 #include <BrowserEngineKit/BrowserEngineKit.h>
 #endif
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 
 namespace ui {
diff --git a/media/audio/BUILD.gn b/media/audio/BUILD.gn
index 8bcbb663710445e977a3080209cd518d3fc2c6e0..0680d3af1f219235e20c0e83b80c0ea9cbf7b3a1 100644
--- a/media/audio/BUILD.gn
+++ b/media/audio/BUILD.gn
@@ -198,6 +198,7 @@ source_set("audio") {
       "CoreMedia.framework",
     ]
     weak_frameworks = [ "ScreenCaptureKit.framework" ]  # macOS 13.0
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_ios) {
diff --git a/media/audio/apple/audio_low_latency_input.cc b/media/audio/apple/audio_low_latency_input.cc
index 098f383475c5958adf02fa3e30c2ba0dcf0a4252..59c958af92ef85bcc329bf0aa69095ca8d2f1d6a 100644
--- a/media/audio/apple/audio_low_latency_input.cc
+++ b/media/audio/apple/audio_low_latency_input.cc
@@ -29,6 +29,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
+#include "electron/mas.h"
 #include "media/audio/apple/audio_manager_apple.h"
 #include "media/audio/apple/scoped_audio_unit.h"
 #include "media/base/audio_bus.h"
@@ -41,19 +42,23 @@
 
 namespace {
 extern "C" {
+#if !IS_MAS_BUILD()
 // See:
 // https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/PAL/pal/spi/cf/CoreAudioSPI.h?rev=228264
 OSStatus AudioDeviceDuck(AudioDeviceID inDevice,
                          Float32 inDuckedLevel,
                          const AudioTimeStamp* __nullable inStartTime,
                          Float32 inRampDuration) __attribute__((weak_import));
+#endif
 }
 
 void UndoDucking(AudioDeviceID output_device_id) {
+#if !IS_MAS_BUILD()
   if (AudioDeviceDuck != nullptr) {
     // Ramp the volume back up over half a second.
     AudioDeviceDuck(output_device_id, 1.0, nullptr, 0.5);
   }
+#endif
 }
 }  // namespace
 #endif
diff --git a/net/dns/BUILD.gn b/net/dns/BUILD.gn
index 543b8ae16c1ddc33b3602adc7216a1756681f5fe..21b2898f8b1f40a85d60145bfdff3aa1d7e9b154 100644
--- a/net/dns/BUILD.gn
+++ b/net/dns/BUILD.gn
@@ -189,6 +189,8 @@ source_set("dns") {
     ":host_resolver_manager",
     ":mdns_client",
   ]
+
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 # The standard API of net/dns.
diff --git a/net/dns/dns_config_service_posix.cc b/net/dns/dns_config_service_posix.cc
index 70d5665ad7b9ef62370497636af919ede2508ad4..f4dc3e2b8053cdb3e8c439ab1a1d6369a8e6a7dc 100644
--- a/net/dns/dns_config_service_posix.cc
+++ b/net/dns/dns_config_service_posix.cc
@@ -28,6 +28,7 @@
 #include "base/threading/scoped_blocking_call.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "electron/mas.h"
 #include "net/base/ip_endpoint.h"
 #include "net/dns/dns_config.h"
 #include "net/dns/dns_hosts.h"
@@ -135,8 +136,8 @@ class DnsConfigServicePosix::Watcher : public DnsConfigService::Watcher {
 
   bool Watch() override {
     CheckOnCorrectSequence();
-
     bool success = true;
+#if !IS_MAS_BUILD()
     if (!config_watcher_.Watch(base::BindRepeating(&Watcher::OnConfigChanged,
                                                    base::Unretained(this)))) {
       LOG(ERROR) << "DNS config watch failed to start.";
@@ -153,6 +154,7 @@ class DnsConfigServicePosix::Watcher : public DnsConfigService::Watcher {
       success = false;
     }
 #endif  // !BUILDFLAG(IS_IOS)
+#endif
     return success;
   }
 
diff --git a/sandbox/mac/BUILD.gn b/sandbox/mac/BUILD.gn
index 453e2185fc85fcb29fa7af3f94cce5bda8118b0c..1c383675bb9113b5b1df9280b8ee994123794dfc 100644
--- a/sandbox/mac/BUILD.gn
+++ b/sandbox/mac/BUILD.gn
@@ -25,6 +25,7 @@ component("seatbelt") {
   libs = [ "sandbox" ]
   deps = [ ":seatbelt_export" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 component("seatbelt_extension") {
@@ -38,6 +39,7 @@ component("seatbelt_extension") {
   libs = [ "sandbox" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 component("system_services") {
@@ -52,6 +54,7 @@ component("system_services") {
   deps = [ ":seatbelt_export" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 source_set("sandbox_unittests") {
diff --git a/sandbox/mac/sandbox_logging.cc b/sandbox/mac/sandbox_logging.cc
index 950cf7cfee4e11766dccf5c0bf3f15a8562f0f1e..a5adaaabdbbd91fedbc4cb679c865bc342536090 100644
--- a/sandbox/mac/sandbox_logging.cc
+++ b/sandbox/mac/sandbox_logging.cc
@@ -21,6 +21,7 @@
 #include <string>
 
 #include "build/build_config.h"
+#include "electron/mas.h"
 #include "sandbox/mac/sandbox_crash_message.h"
 
 #if defined(ARCH_CPU_X86_64)
@@ -38,9 +39,11 @@
   }
 #endif
 
+#if !IS_MAS_BUILD()
 extern "C" {
 void abort_report_np(const char*, ...);
 }
+#endif
 
 namespace sandbox::logging {
 
@@ -81,9 +84,11 @@ void SendOsLog(Level level, const char* message) {
     sandbox::crash_message::SetCrashMessage(message);
   }
 
+#if !IS_MAS_BUILD()
   if (level == Level::FATAL) {
     abort_report_np(message);
   }
+#endif
 }
 
 // |error| is strerror(errno) when a P* logging function is called. Pass
diff --git a/sandbox/mac/sandbox_serializer.cc b/sandbox/mac/sandbox_serializer.cc
index 899f231e9bc8e1c76682972dd3f41d4cc38f4868..1da42104cc82cbabfd0c14fdd7025d6963aa50d6 100644
--- a/sandbox/mac/sandbox_serializer.cc
+++ b/sandbox/mac/sandbox_serializer.cc
@@ -7,6 +7,7 @@
 #include <string>
 #include <vector>
 
+#include "electron/mas.h"
 #include "sandbox/mac/sandbox_logging.h"
 #include "sandbox/mac/seatbelt.h"
 
@@ -31,6 +32,7 @@ void EncodeVarInt(uint64_t from, std::string* into) {
   } while (from);
 }
 
+#if !IS_MAS_BUILD()
 bool DecodeVarInt(std::string_view* from, uint64_t* into) {
   std::string_view::const_iterator it = from->begin();
   int shift = 0;
@@ -49,12 +51,12 @@ bool DecodeVarInt(std::string_view* from, uint64_t* into) {
   from->remove_prefix(it - from->begin());
   return true;
 }
-
+#endif
 void EncodeString(const std::string& value, std::string* into) {
   EncodeVarInt(value.length(), into);
   into->append(value);
 }
-
+#if !IS_MAS_BUILD()
 bool DecodeString(std::string_view* slice, std::string* value) {
   uint64_t length;
   if (!DecodeVarInt(slice, &length) || length < 0) {
@@ -69,7 +71,7 @@ bool DecodeString(std::string_view* slice, std::string* value) {
   slice->remove_prefix(size);
   return true;
 }
-
+#endif
 }  // namespace
 
 SandboxSerializer::SandboxSerializer(Target mode) : mode_(mode) {
@@ -140,6 +142,7 @@ bool SandboxSerializer::SerializePolicy(std::string& serialized_policy,
 // static
 bool SandboxSerializer::ApplySerializedPolicy(
     const std::string& serialized_policy) {
+#if !IS_MAS_BUILD()
   std::string_view policy = serialized_policy;
   uint64_t mode;
   if (!DecodeVarInt(&policy, &mode)) {
@@ -201,6 +204,9 @@ bool SandboxSerializer::ApplySerializedPolicy(
   }
 
   return true;
+#else
+  return true;
+#endif
 }
 
 }  // namespace sandbox
diff --git a/sandbox/mac/seatbelt.cc b/sandbox/mac/seatbelt.cc
index 1960e1c8771fad615a098af09ff1f9a191f67764..29b97b352d08cd1fe73b17fd80cb41cc7e58dcaa 100644
--- a/sandbox/mac/seatbelt.cc
+++ b/sandbox/mac/seatbelt.cc
@@ -4,12 +4,14 @@
 
 #include "sandbox/mac/seatbelt.h"
 
+#include "electron/mas.h"
+
 #include <errno.h>
 #include <unistd.h>
 
 extern "C" {
 #include <sandbox.h>
-
+#if !IS_MAS_BUILD()
 int sandbox_init_with_parameters(const char* profile,
                                  uint64_t flags,
                                  const char* const parameters[],
@@ -40,13 +42,13 @@ sandbox_profile_t* sandbox_compile_string(const char* data,
                                           char** error);
 int sandbox_apply(sandbox_profile_t*);
 void sandbox_free_profile(sandbox_profile_t*);
-
+#endif
 }  // extern "C"
 
 namespace sandbox {
 
 namespace {
-
+#if !IS_MAS_BUILD()
 bool HandleSandboxResult(int rv, char* errorbuf, std::string* error) {
   if (rv == 0) {
     if (error)
@@ -74,36 +76,48 @@ bool HandleSandboxErrno(int rv, const char* message, std::string* error) {
   }
   return false;
 }
-
+#endif
 }  // namespace
 
 // static
 Seatbelt::Parameters Seatbelt::Parameters::Create() {
   Parameters params;
+#if !IS_MAS_BUILD()
   params.params_ = ::sandbox_create_params();
+#endif
   return params;
 }
 
 Seatbelt::Parameters::Parameters() = default;
 
 Seatbelt::Parameters::Parameters(Seatbelt::Parameters&& other) {
+#if !IS_MAS_BUILD()
   params_ = std::exchange(other.params_, nullptr);
+#endif
 }
 
 Seatbelt::Parameters& Seatbelt::Parameters::operator=(
     Seatbelt::Parameters&& other) {
+#if !IS_MAS_BUILD()
   params_ = std::exchange(other.params_, nullptr);
+#endif
   return *this;
 }
 
 bool Seatbelt::Parameters::Set(const char* key, const char* value) {
+#if !IS_MAS_BUILD()
   return ::sandbox_set_param(params_, key, value) == 0;
+#else
+  return true;
+#endif
 }
 
 Seatbelt::Parameters::~Parameters() {
+#if !IS_MAS_BUILD()
   if (params_) {
     ::sandbox_free_params(params_);
   }
+#endif
 }
 
 // Initialize the static member variables.
@@ -114,6 +128,7 @@ const char* Seatbelt::kProfilePureComputation = kSBXProfilePureComputation;
 
 // static
 bool Seatbelt::Init(const char* profile, uint64_t flags, std::string* error) {
+#if !IS_MAS_BUILD()
 // OS X deprecated these functions, but did not provide a suitable replacement,
 // so ignore the deprecation warning.
 #pragma clang diagnostic push
@@ -122,6 +137,9 @@ bool Seatbelt::Init(const char* profile, uint64_t flags, std::string* error) {
   int rv = ::sandbox_init(profile, flags, &errorbuf);
   return HandleSandboxResult(rv, errorbuf, error);
 #pragma clang diagnostic pop
+#else
+  return true;
+#endif
 }
 
 // static
@@ -129,16 +147,21 @@ bool Seatbelt::InitWithParams(const std::string& profile,
                               uint64_t flags,
                               const std::vector<std::string>& parameters,
                               std::string* error) {
+#if !IS_MAS_BUILD()
   std::vector<const char*> weak_params;
   for (const std::string& param : parameters) {
     weak_params.push_back(param.c_str());
   }
   // The parameters array must be null terminated.
   weak_params.push_back(nullptr);
+
   char* errorbuf = nullptr;
   int rv = ::sandbox_init_with_parameters(profile.c_str(), flags,
                                           weak_params.data(), &errorbuf);
   return HandleSandboxResult(rv, errorbuf, error);
+#else
+  return true;
+#endif
 }
 
 // static
@@ -146,6 +169,7 @@ bool Seatbelt::Compile(const char* profile,
                        const Seatbelt::Parameters& params,
                        std::string& compiled_profile,
                        std::string* error) {
+#if !IS_MAS_BUILD()
   char* errorbuf = nullptr;
   sandbox_profile_t* sandbox_profile =
       ::sandbox_compile_string(profile, params.params(), &errorbuf);
@@ -155,33 +179,44 @@ bool Seatbelt::Compile(const char* profile,
   compiled_profile.assign(reinterpret_cast<const char*>(sandbox_profile->data),
                           sandbox_profile->size);
   ::sandbox_free_profile(sandbox_profile);
+#endif
   return true;
 }
 
 // static
 bool Seatbelt::ApplyCompiledProfile(const std::string& profile,
                                     std::string* error) {
+#if !IS_MAS_BUILD()
   sandbox_profile_t sbox_profile = {
       .builtin = nullptr,
       .data = reinterpret_cast<const uint8_t*>(profile.data()),
       .size = profile.size()};
   return HandleSandboxErrno(::sandbox_apply(&sbox_profile),
                             "sandbox_apply: ", error);
+#else
+  return true;
+#endif
 }
 
 // static
 void Seatbelt::FreeError(char* errorbuf) {
+#if !IS_MAS_BUILD()
 // OS X deprecated these functions, but did not provide a suitable replacement,
 // so ignore the deprecation warning.
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
   return ::sandbox_free_error(errorbuf);
 #pragma clang diagnostic pop
+#endif
 }
 
 // static
 bool Seatbelt::IsSandboxed() {
+#if !IS_MAS_BUILD()
   return ::sandbox_check(getpid(), NULL, 0);
+#else
+  return true;
+#endif
 }
 
 }  // namespace sandbox
diff --git a/sandbox/mac/seatbelt_extension.cc b/sandbox/mac/seatbelt_extension.cc
index 79edca9ca521d1bc2ff343967348eb98039b292a..23f9410ee66024e2c6b0b6b2b356a67b0ae2eba7 100644
--- a/sandbox/mac/seatbelt_extension.cc
+++ b/sandbox/mac/seatbelt_extension.cc
@@ -9,8 +9,10 @@
 #include "base/check.h"
 #include "base/memory/ptr_util.h"
 #include "base/notreached.h"
+#include "electron/mas.h"
 #include "sandbox/mac/seatbelt_extension_token.h"
 
+#if !IS_MAS_BUILD()
 // libsandbox private API.
 extern "C" {
 extern const char* APP_SANDBOX_READ;
@@ -22,6 +24,7 @@ char* sandbox_extension_issue_file(const char* type,
                                    const char* path,
                                    uint32_t flags);
 }
+#endif
 
 namespace sandbox {
 
@@ -50,7 +53,11 @@ std::unique_ptr<SeatbeltExtension> SeatbeltExtension::FromToken(
 
 bool SeatbeltExtension::Consume() {
   DCHECK(!token_.empty());
+#if !IS_MAS_BUILD()
   handle_ = sandbox_extension_consume(token_.c_str());
+#else
+  handle_ = -1;
+#endif
   return handle_ > 0;
 }
 
@@ -62,7 +69,11 @@ bool SeatbeltExtension::ConsumePermanently() {
 }
 
 bool SeatbeltExtension::Revoke() {
+#if !IS_MAS_BUILD()
   int rv = sandbox_extension_release(handle_);
+#else
+  int rv = -1;
+#endif
   handle_ = 0;
   token_.clear();
   return rv == 0;
@@ -80,12 +91,14 @@ SeatbeltExtension::SeatbeltExtension(const std::string& token)
 char* SeatbeltExtension::IssueToken(SeatbeltExtension::Type type,
                                     const std::string& resource) {
   switch (type) {
+#if !IS_MAS_BUILD()
     case FILE_READ:
       return sandbox_extension_issue_file(APP_SANDBOX_READ, resource.c_str(),
                                           0);
     case FILE_READ_WRITE:
       return sandbox_extension_issue_file(APP_SANDBOX_READ_WRITE,
                                           resource.c_str(), 0);
+#endif
     default:
       NOTREACHED();
   }
diff --git a/sandbox/mac/system_services.cc b/sandbox/mac/system_services.cc
index eb81a70e4d5d5cd3e6ae9b45f8cd1c795ea76c51..9921ccb10d3455600eddd85f77f10228016389af 100644
--- a/sandbox/mac/system_services.cc
+++ b/sandbox/mac/system_services.cc
@@ -8,7 +8,9 @@
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/apple/osstatus_logging.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 OSStatus SetApplicationIsDaemon(Boolean isDaemon);
 void _LSSetApplicationLaunchServicesServerConnectionStatus(
@@ -19,10 +21,12 @@ void _LSSetApplicationLaunchServicesServerConnectionStatus(
 // https://github.com/WebKit/WebKit/blob/24aaedc770d192d03a07ba4a71727274aaa8fc07/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm#L840
 void _CSCheckFixDisable();
 }  // extern "C"
+#endif
 
 namespace sandbox {
 
 void DisableLaunchServices() {
+  #if !IS_MAS_BUILD()
   // Allow the process to continue without a LaunchServices ASN. The
   // INIT_Process function in HIServices will abort if it cannot connect to
   // launchservicesd to get an ASN. By setting this flag, HIServices skips
@@ -36,10 +40,13 @@ void DisableLaunchServices() {
       0, ^bool(CFDictionaryRef options) {
         return false;
       });
+  #endif
 }
 
 void DisableCoreServicesCheckFix() {
+#if !IS_MAS_BUILD()
   _CSCheckFixDisable();
+#endif
 }
 
 }  // namespace sandbox
diff --git a/third_party/blink/renderer/core/BUILD.gn b/third_party/blink/renderer/core/BUILD.gn
index 3ff395b3ff3b646a64c43503d2c172776bf68c84..e40030307e8d9df7e00a402e241e00664b236c7d 100644
--- a/third_party/blink/renderer/core/BUILD.gn
+++ b/third_party/blink/renderer/core/BUILD.gn
@@ -414,6 +414,7 @@ component("core") {
     "//ui/gfx/geometry",
     "//ui/gfx/geometry:geometry_skia",
     "//ui/strings",
+    "//electron/build/config:generate_mas_config",
   ]
 
   if (is_mac) {
diff --git a/third_party/blink/renderer/core/editing/build.gni b/third_party/blink/renderer/core/editing/build.gni
index d38e951cdbf1ab9b367273ad0fb8f962155a7f3b..e39ee0414cb54004096dbfffc4f768e805f3310a 100644
--- a/third_party/blink/renderer/core/editing/build.gni
+++ b/third_party/blink/renderer/core/editing/build.gni
@@ -358,10 +358,14 @@ blink_core_sources_editing = [
 if (is_mac) {
   blink_core_sources_editing += [
     "commands/smart_replace_cf.cc",
-    "kill_ring_mac.mm",
     "substring_util.h",
     "substring_util.mm",
   ]
+  if (is_mas_build) {
+    blink_core_sources_editing += [ "kill_ring_mac.mm" ]
+  } else {
+    blink_core_sources_editing += [ "kill_ring_none.cc" ]
+  }
 } else {
   blink_core_sources_editing += [ "kill_ring_none.cc" ]
 }
diff --git a/ui/accelerated_widget_mac/BUILD.gn b/ui/accelerated_widget_mac/BUILD.gn
index ce3dc22f38b9d3f2f12e469b23f5dfe06ecbb98a..a69af46e05365028379dbf6abafaacd9b19e4569 100644
--- a/ui/accelerated_widget_mac/BUILD.gn
+++ b/ui/accelerated_widget_mac/BUILD.gn
@@ -77,6 +77,7 @@ component("accelerated_widget_mac") {
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
+    "//electron/build/config:generate_mas_config",
   ]
 }
 
diff --git a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
index a615405dac100a08234b43f5ec354fb829bb5222..3cf40179700a4d5b69e18993b923f8f14919f9fa 100644
--- a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
+++ b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
@@ -7,6 +7,7 @@
 
 #include <queue>
 
+#include "electron/mas.h"
 #include "ui/accelerated_widget_mac/accelerated_widget_mac_export.h"
 #include "ui/accelerated_widget_mac/ca_renderer_layer_tree.h"
 #include "ui/gfx/ca_layer_result.h"
@@ -14,7 +15,9 @@
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/presenter.h"
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 
 namespace ui {
@@ -110,7 +113,9 @@ class ACCELERATED_WIDGET_MAC_EXPORT CALayerTreeCoordinator {
   // both the current tree and the pending trees.
   size_t presented_ca_layer_trees_max_length_ = 2;
 
+#if !IS_MAS_BUILD()
   CAContext* __strong ca_context_;
+#endif
 
   // The root CALayer to display the current frame. This does not change
   // over the lifetime of the object.
diff --git a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
index cfb80b21ada7f04ff615b0437403ac1c6c95bb14..34341007de140aba2e6eeb9d8e8de0ea492c2466 100644
--- a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
+++ b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
@@ -10,6 +10,7 @@
 #include "base/mac/mac_util.h"
 #include "base/task/single_thread_task_runner.h"
 #include "base/trace_event/trace_event.h"
+#include "electron/mas.h"
 #include "ui/base/cocoa/animation_utils.h"
 #include "ui/base/cocoa/remote_layer_api.h"
 #include "ui/gfx/ca_layer_params.h"
@@ -30,6 +31,7 @@
       allow_av_sample_buffer_display_layer_(
           allow_av_sample_buffer_display_layer),
       buffer_presented_callback_(buffer_presented_callback) {
+#if !IS_MAS_BUILD()
   if (allow_remote_layers_) {
     root_ca_layer_ = [[CALayer alloc] init];
 #if BUILDFLAG(IS_MAC)
@@ -58,6 +60,7 @@
 #endif
     ca_context_.layer = root_ca_layer_;
   }
+#endif
 }
 
 CALayerTreeCoordinator::~CALayerTreeCoordinator() = default;
@@ -161,9 +164,13 @@
     TRACE_EVENT_INSTANT2("test_gpu", "SwapBuffers", TRACE_EVENT_SCOPE_THREAD,
                          "GLImpl", static_cast<int>(gl::GetGLImplementation()),
                          "width", pixel_size_.width());
+#if !IS_MAS_BUILD()
     if (allow_remote_layers_) {
       params.ca_context_id = [ca_context_ contextId];
     } else {
+#else
+    if (true) {
+#endif
       IOSurfaceRef io_surface = frame->layer_tree->GetContentIOSurface();
       if (io_surface) {
         DCHECK(!allow_remote_layers_);
diff --git a/ui/accelerated_widget_mac/display_ca_layer_tree.mm b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
index dcf493d62990018040a3f84b6f875af737bd2214..3d1c4dcc9ee0bbfdac15f40d9c74e9f342a59e39 100644
--- a/ui/accelerated_widget_mac/display_ca_layer_tree.mm
+++ b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
@@ -12,6 +12,7 @@
 #include "base/mac/mac_util.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
+#include "electron/mas.h"
 #include "ui/base/cocoa/animation_utils.h"
 #include "ui/base/cocoa/remote_layer_api.h"
 #include "ui/gfx/geometry/dip_util.h"
@@ -121,6 +122,7 @@ - (void)setContentsChanged;
 }
 
 void DisplayCALayerTree::GotCALayerFrame(uint32_t ca_context_id) {
+#if !IS_MAS_BUILD()
   // Early-out if the remote layer has not changed.
   if (remote_layer_.contextId == ca_context_id) {
     return;
@@ -150,6 +152,9 @@ - (void)setContentsChanged;
     [io_surface_layer_ removeFromSuperlayer];
     io_surface_layer_ = nil;
   }
+#else
+  NOTREACHED() << "Remote layer is being used in MAS build";
+#endif
 }
 
 void DisplayCALayerTree::GotIOSurfaceFrame(
diff --git a/ui/accessibility/platform/BUILD.gn b/ui/accessibility/platform/BUILD.gn
index 30440d1b5ba071c8cf2076e7e7acb24681f78a2f..ca18e61ff2eb743fabeb10af06c208f84b526dd8 100644
--- a/ui/accessibility/platform/BUILD.gn
+++ b/ui/accessibility/platform/BUILD.gn
@@ -295,6 +295,7 @@ component("platform") {
         "AppKit.framework",
         "Foundation.framework",
       ]
+      deps += ["//electron/build/config:generate_mas_config"]
     }
 
     if (is_ios) {
diff --git a/ui/accessibility/platform/browser_accessibility_manager_mac.mm b/ui/accessibility/platform/browser_accessibility_manager_mac.mm
index 6d4f3f6f0b4419d6572704dd127965b8df5b5949..0b7d8e68ec1f24e307c6fad6a55aecc3ec7b4690 100644
--- a/ui/accessibility/platform/browser_accessibility_manager_mac.mm
+++ b/ui/accessibility/platform/browser_accessibility_manager_mac.mm
@@ -14,6 +14,7 @@
 #include "base/task/single_thread_task_runner.h"
 #include "base/task/task_traits.h"
 #include "base/time/time.h"
+#include "electron/mas.h"
 #include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
 #include "ui/accessibility/accessibility_features.h"
 #include "ui/accessibility/ax_role_properties.h"
@@ -21,7 +22,9 @@
 #include "ui/accessibility/platform/ax_private_webkit_constants_mac.h"
 #import "ui/accessibility/platform/browser_accessibility_cocoa.h"
 #import "ui/accessibility/platform/browser_accessibility_mac.h"
+#if !IS_MAS_BUILD()
 #include "ui/base/cocoa/remote_accessibility_api.h"
+#endif
 
 namespace {
 
@@ -230,6 +233,7 @@ void PostAnnouncementNotification(NSString* announcement,
         return;
       }
 
+#if !IS_MAS_BUILD()
       BrowserAccessibilityManager* root_manager = GetManagerForRootFrame();
       if (root_manager) {
         BrowserAccessibilityManagerMac* root_manager_mac =
@@ -252,6 +256,7 @@ void PostAnnouncementNotification(NSString* announcement,
           return;
         }
       }
+#endif
 
       // Use native VoiceOver support for live regions.
       BrowserAccessibilityCocoa* retained_node = native_node;
@@ -668,6 +673,7 @@ void PostAnnouncementNotification(NSString* announcement,
     return window == [NSApp accessibilityFocusedWindow];
   }
 
+#if !IS_MAS_BUILD()
   // TODO(accessibility): We need a solution to the problem described below.
   // If the window is NSAccessibilityRemoteUIElement, there are some challenges:
   // 1. NSApp is the browser which spawned the PWA, and what it considers the
@@ -696,6 +702,7 @@ void PostAnnouncementNotification(NSString* announcement,
   if ([window isKindOfClass:[NSAccessibilityRemoteUIElement class]]) {
     return true;
   }
+#endif
 
   return false;
 }
diff --git a/ui/accessibility/platform/inspect/ax_transform_mac.mm b/ui/accessibility/platform/inspect/ax_transform_mac.mm
index 6846060ef9622d8fc8d1d6c8da16e2f1b785e6bd..05c22db87e882b246bd7034e027cf1495376b6c6 100644
--- a/ui/accessibility/platform/inspect/ax_transform_mac.mm
+++ b/ui/accessibility/platform/inspect/ax_transform_mac.mm
@@ -11,6 +11,7 @@
 
 #include "base/apple/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
+#include "electron/mas.h"
 #include "ui/accessibility/ax_range.h"
 #include "ui/accessibility/platform/ax_platform_node.h"
 #include "ui/accessibility/platform/ax_platform_node_cocoa.h"
@@ -111,6 +112,7 @@
     }
   }
 
+#if !IS_MAS_BUILD()
   // AXTextMarker
   if (IsAXTextMarker(value)) {
     return AXTextMarkerToBaseValue(value, indexer);
@@ -120,6 +122,7 @@
   if (IsAXTextMarkerRange(value)) {
     return AXTextMarkerRangeToBaseValue(value, indexer);
   }
+#endif
 
   // Accessible object
   if (AXElementWrapper::IsValidElement(value)) {
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index 8abb389faddb435980c1c06c3d69e33d5bf13881..62bb9b60b54252a44590616142a0beabbf6b55bf 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -365,6 +365,13 @@ component("base") {
     ]
   }
 
+  if (is_mas_build) {
+    sources -= [
+      "cocoa/remote_accessibility_api.h",
+      "cocoa/remote_accessibility_api.mm",
+    ]
+  }
+
   if (is_ios) {
     sources += [
       "device_form_factor_ios.mm",
@@ -518,6 +525,12 @@ component("base") {
     "//url",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config"
+    ]
+  }
+
   if (is_debug || dcheck_always_on) {
     deps += [ "//third_party/re2" ]
   }
diff --git a/ui/base/cocoa/remote_accessibility_api.h b/ui/base/cocoa/remote_accessibility_api.h
index 3182458838aa96d34911280ab4c6c3aa4aa22d6d..6dc85c366b7e61c8bd0302e501c3223a19223313 100644
--- a/ui/base/cocoa/remote_accessibility_api.h
+++ b/ui/base/cocoa/remote_accessibility_api.h
@@ -10,9 +10,12 @@
 #include <vector>
 
 #include "base/component_export.h"
+#include "electron/mas.h"
 
 // NSAccessibilityRemoteUIElement is a private class in AppKit.
 
+#if !IS_MAS_BUILD()
+
 @interface NSAccessibilityRemoteUIElement : NSObject
 + (void)setRemoteUIApp:(BOOL)flag;
 + (BOOL)isRemoteUIApp;
@@ -38,4 +41,6 @@ class COMPONENT_EXPORT(UI_BASE) RemoteAccessibility {
 
 }  // namespace ui
 
+#endif  // MAS_BUILD
+
 #endif  // UI_BASE_COCOA_REMOTE_ACCESSIBILITY_API_H_
diff --git a/ui/base/cocoa/remote_layer_api.h b/ui/base/cocoa/remote_layer_api.h
index 59dc2f82214cfd883b6ebef3b0fb25af6387a9cd..912c5252d1b30d943a1552739b9eef9a8eae2d7a 100644
--- a/ui/base/cocoa/remote_layer_api.h
+++ b/ui/base/cocoa/remote_layer_api.h
@@ -9,6 +9,7 @@
 
 #include "base/component_export.h"
 #include "build/build_config.h"
+#include "electron/mas.h"
 
 #if defined(__OBJC__)
 #import <Foundation/Foundation.h>
@@ -17,6 +18,7 @@
 
 #if BUILDFLAG(IS_MAC)
 
+#if !IS_MAS_BUILD()
 // The CGSConnectionID is used to create the CAContext in the process that is
 // going to share the CALayers that it is rendering to another process to
 // display.
@@ -68,6 +70,8 @@ extern NSString* const kCAContextIgnoresHitTest;
 
 #endif  // __OBJC__
 
+#endif // MAS_BUILD
+
 namespace ui {
 
 // This function will check if all of the interfaces listed above are supported
diff --git a/ui/base/cocoa/remote_layer_api.mm b/ui/base/cocoa/remote_layer_api.mm
index fc25ba79d2b0e1acdb7ba54b89e7d6e16f94771b..de771ef414b9a69e331261524f08e9a12145ec60 100644
--- a/ui/base/cocoa/remote_layer_api.mm
+++ b/ui/base/cocoa/remote_layer_api.mm
@@ -5,11 +5,13 @@
 #include "ui/base/cocoa/remote_layer_api.h"
 
 #include "base/feature_list.h"
+#include "electron/mas.h"
 
 #include <objc/runtime.h>
 
 namespace ui {
 
+#if !IS_MAS_BUILD()
 namespace {
 // Control use of cross-process CALayers to display content directly from the
 // GPU process on Mac.
@@ -17,8 +19,10 @@
              "RemoteCoreAnimationAPI",
              base::FEATURE_ENABLED_BY_DEFAULT);
 }  // namespace
+#endif
 
 bool RemoteLayerAPISupported() {
+#if !IS_MAS_BUILD()
   if (!base::FeatureList::IsEnabled(kRemoteCoreAnimationAPI))
     return false;
 
@@ -55,6 +59,9 @@ bool RemoteLayerAPISupported() {
 
   // If everything is there, we should be able to use the API.
   return true;
+#else
+  return false;
+#endif  // MAS_BUILD
 }
 
 }  // namespace
diff --git a/ui/display/BUILD.gn b/ui/display/BUILD.gn
index e598004da50257f4ee37a6431222c2b9e9f24b62..3f2ea7a469d6580d25fe51b657555d77a9ce9b80 100644
--- a/ui/display/BUILD.gn
+++ b/ui/display/BUILD.gn
@@ -127,6 +127,12 @@ component("display") {
     "//ui/gfx/geometry",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config"
+    ]
+  }
+
   if (is_ios) {
     deps += [ "//build:ios_buildflags" ]
   }
diff --git a/ui/display/mac/screen_mac.mm b/ui/display/mac/screen_mac.mm
index 874ac9d572931fe175ccab8beb7738fe0a7b3c1b..b70e2a8a7be9e00a379f47c77589dde6b8b1f081 100644
--- a/ui/display/mac/screen_mac.mm
+++ b/ui/display/mac/screen_mac.mm
@@ -30,6 +30,7 @@
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "components/device_event_log/device_event_log.h"
+#include "electron/mas.h"
 #include "ui/display/display.h"
 #include "ui/display/display_change_notifier.h"
 #include "ui/display/util/display_util.h"
@@ -177,7 +178,17 @@ DisplayMac BuildDisplayForScreen(NSScreen* screen) {
     display.set_color_depth(Display::kDefaultBitsPerPixel);
     display.set_depth_per_component(Display::kDefaultBitsPerComponent);
   }
+#if IS_MAS_BUILD()
+  // This is equivalent to the CGDisplayUsesForceToGray() API as at 2018-08-06,
+  // but avoids usage of the private API.
+  CFStringRef app = CFSTR("com.apple.CoreGraphics");
+  CFStringRef key = CFSTR("DisplayUseForcedGray");
+  Boolean key_valid = false;
+  display.set_is_monochrome(
+      CFPreferencesGetAppBooleanValue(key, app, &key_valid));
+#else
   display.set_is_monochrome(CGDisplayUsesForceToGray());
+#endif
 
   // Query the display's refresh rate.
   if (@available(macos 12.0, *)) {
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index e531cb42cde9863ff1c4a13150f35877b564226c..0c0ec308be02297b090d08b52cc713c22652da36 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -337,6 +337,12 @@ component("gfx") {
     "//ui/base:ui_data_pack",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config"
+    ]
+  }
+
   if (!is_apple) {
     sources += [
       "platform_font_skia.cc",
diff --git a/ui/gfx/platform_font_mac.mm b/ui/gfx/platform_font_mac.mm
index fe3f85073e31de487a08e57d7f9b07aa4eccf8f3..cf5b07203c8bd559a404600cc98cc8eccdefd4d7 100644
--- a/ui/gfx/platform_font_mac.mm
+++ b/ui/gfx/platform_font_mac.mm
@@ -19,6 +19,7 @@
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
+#include "electron/mas.h"
 #include "third_party/skia/include/ports/SkTypeface_mac.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/font.h"
@@ -28,9 +29,11 @@
 
 using Weight = Font::Weight;
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CTFontDescriptorIsSystemUIFont(CTFontDescriptorRef);
 }
+#endif
 
 namespace {
 
@@ -250,7 +253,13 @@ CTFontRef SystemFontForConstructorOfType(
   // TODO(avi, etienneb): Figure out this font stuff.
   base::apple::ScopedCFTypeRef<CTFontDescriptorRef> descriptor(
       CTFontCopyFontDescriptor(font));
+#if IS_MAS_BUILD()
+  CFNumberRef priority = (CFNumberRef)CTFontDescriptorCopyAttribute(descriptor.get(), (CFStringRef)kCTFontPriorityAttribute);
+  SInt64 v;
+  if (CFNumberGetValue(priority, kCFNumberSInt64Type, &v) && v == kCTFontPrioritySystem) {
+#else
   if (CTFontDescriptorIsSystemUIFont(descriptor.get())) {
+#endif
     // Assume it's the standard system font. The fact that this much is known is
     // enough.
     return PlatformFontMac::SystemFontType::kGeneral;
diff --git a/ui/views/BUILD.gn b/ui/views/BUILD.gn
index a8f20a694252ae90eb6c6c7d77d250dcdb2df1a3..8e3f87df5e1345ddeb12cb424abaf3a442798320 100644
--- a/ui/views/BUILD.gn
+++ b/ui/views/BUILD.gn
@@ -715,6 +715,8 @@ component("views") {
       "IOSurface.framework",
       "QuartzCore.framework",
     ]
+
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_win) {
@@ -1142,6 +1144,8 @@ source_set("test_support") {
     "//ui/base/mojom:ui_base_types",
   ]
 
+  deps += ["//electron/build/config:generate_mas_config"]
+
   if (is_win) {
     sources += [
       "test/desktop_window_tree_host_win_test_api.cc",
diff --git a/ui/views/cocoa/native_widget_mac_ns_window_host.h b/ui/views/cocoa/native_widget_mac_ns_window_host.h
index cbd0b7708a7afd39852a7f75a21173d5b8a71a5e..1e8d5b3f66992a6bcbecd7149c45982319076d0c 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.h
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.h
@@ -18,6 +18,7 @@
 #include "components/remote_cocoa/browser/scoped_cg_window_id.h"
 #include "components/remote_cocoa/common/native_widget_ns_window.mojom.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_receiver.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
@@ -33,7 +34,9 @@
 #include "ui/views/window/dialog_observer.h"
 
 @class NativeWidgetMacNSWindow;
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class NSView;
 
 namespace remote_cocoa {
@@ -489,10 +492,12 @@ class VIEWS_EXPORT NativeWidgetMacNSWindowHost
   mojo::AssociatedRemote<remote_cocoa::mojom::NativeWidgetNSWindow>
       remote_ns_window_remote_;
 
+#if !IS_MAS_BUILD()
   // Remote accessibility objects corresponding to the NSWindow and its root
   // NSView.
   NSAccessibilityRemoteUIElement* __strong remote_window_accessible_;
   NSAccessibilityRemoteUIElement* __strong remote_view_accessible_;
+#endif
 
   // Used to force the NSApplication's focused accessibility element to be the
   // views::Views accessibility tree when the NSView for this is focused.
diff --git a/ui/views/cocoa/native_widget_mac_ns_window_host.mm b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
index 22ac01614becd53955914c44be13886d775b683e..235899693e2f2d340cc63df1ded3dfe3c9775cee 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.mm
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
@@ -21,6 +21,7 @@
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/browser/ns_view_ids.h"
 #include "components/remote_cocoa/browser/window.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/self_owned_associated_receiver.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
 #include "ui/accessibility/accessibility_features.h"
@@ -357,8 +358,12 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   if (in_process_ns_window_bridge_) {
     return gfx::NativeViewAccessible(in_process_ns_window_bridge_->ns_view());
   }
+#if !IS_MAS_BUILD()
   return gfx::NativeViewAccessible(
       (id<NSAccessibility>)remote_view_accessible_);
+#else
+  return {};
+#endif
 }
 
 gfx::NativeViewAccessible
@@ -374,8 +379,12 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
         [in_process_ns_window_bridge_->ns_view() window]);
   }
 
+#if !IS_MAS_BUILD()
   return gfx::NativeViewAccessible(
       (id<NSAccessibility>)remote_window_accessible_);
+#else
+  return {};
+#endif
 }
 
 remote_cocoa::mojom::NativeWidgetNSWindow*
@@ -1387,9 +1396,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   // for PWAs. However this breaks accessibility on in-process windows,
   // so set it back to NO when a local window gains focus. See
   // https://crbug.com/41485830.
+#if !IS_MAS_BUILD()
   if (is_key && features::IsAccessibilityRemoteUIAppEnabled()) {
     [NSAccessibilityRemoteUIElement setRemoteUIApp:!!application_host_];
   }
+#endif
   // Explicitly set the keyboard accessibility state on regaining key
   // window status.
   if (is_key && is_content_first_responder) {
@@ -1530,17 +1541,20 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
 void NativeWidgetMacNSWindowHost::SetRemoteAccessibilityTokens(
     const std::vector<uint8_t>& window_token,
     const std::vector<uint8_t>& view_token) {
+#if !IS_MAS_BUILD()
   remote_window_accessible_ =
       ui::RemoteAccessibility::GetRemoteElementFromToken(window_token);
   remote_view_accessible_ =
       ui::RemoteAccessibility::GetRemoteElementFromToken(view_token);
   [remote_view_accessible_ setWindowUIElement:remote_window_accessible_];
   [remote_view_accessible_ setTopLevelUIElement:remote_window_accessible_];
+#endif
 }
 
 bool NativeWidgetMacNSWindowHost::GetRootViewAccessibilityToken(
     base::ProcessId* pid,
     std::vector<uint8_t>* token) {
+#if !IS_MAS_BUILD()
   *pid = getpid();
   id element_id = GetNativeViewAccessible();
 
@@ -1553,6 +1567,7 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   }
 
   *token = ui::RemoteAccessibility::GetTokenForLocalElement(element_id);
+#endif
   return true;
 }
 
diff --git a/ui/views/controls/webview/BUILD.gn b/ui/views/controls/webview/BUILD.gn
index 111d6432586f47833dde50678b908c76ad88d37a..429ca4402652a2d89ead228d92971f0cb3b6222c 100644
--- a/ui/views/controls/webview/BUILD.gn
+++ b/ui/views/controls/webview/BUILD.gn
@@ -46,6 +46,12 @@ component("webview") {
     "//url",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config",
+    ]
+  }
+
   public_deps = [
     "//base",
     "//content/public/browser",