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 a989a351a87650d33342cc8eea9d719bcad31fb6..6c8cfaec9e3034d7f05d257211bfdd8172b0136b 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1053,6 +1053,7 @@ component("base") {
     "//build/config/compiler:prevent_unsafe_narrowing",
     "//build/config/compiler:wexit_time_destructors",
     "//build/config/compiler:wglobal_constructors",
+    "//electron/build/config:mas_build",
   ]
 
   deps = [
diff --git a/base/enterprise_util_mac.mm b/base/enterprise_util_mac.mm
index 2bad2ed2f5205b3a2599aa3a620812aa32d52f87..ab3d4c953556d4f94075671436565a6c442f30d5 100644
--- a/base/enterprise_util_mac.mm
+++ b/base/enterprise_util_mac.mm
@@ -115,6 +115,14 @@ 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) {
@@ -218,5 +226,6 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
 
   return state;
 }
+#endif
 
 }  // namespace base
diff --git a/base/process/launch_mac.cc b/base/process/launch_mac.cc
index b267bc2272fa82334a70d897a900f1ea37b1a598..967e22699bf565368704972c021f9b425a570f08 100644
--- a/base/process/launch_mac.cc
+++ b/base/process/launch_mac.cc
@@ -21,13 +21,18 @@
 #include "base/threading/scoped_blocking_call.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/trace_event/base_tracing.h"
+#if IS_MAS_BUILD()
+#include <sys/syscall.h>
+#endif
 
 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);
@@ -99,13 +104,27 @@ 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
 
@@ -226,7 +245,7 @@ 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.cc b/base/process/process_info_mac.cc
index 94a028be3c315edc0056408ab9ab41b6b001a1c1..0d830234edb5621f57e39f4a951d357a23f677c1 100644
--- a/base/process/process_info_mac.cc
+++ b/base/process/process_info_mac.cc
@@ -8,15 +8,21 @@
 #include <stdlib.h>
 #include <unistd.h>
 
+#if !IS_MAS_BUILD()
 extern "C" {
 pid_t responsibility_get_pid_responsible_for_pid(pid_t);
 }
+#endif
 
 namespace base {
 
 bool IsProcessSelfResponsible() {
+#if !IS_MAS_BUILD()
   const pid_t pid = getpid();
   return responsibility_get_pid_responsible_for_pid(pid) == pid;
+#else
+  return true;
+#endif
 }
 
 }  // namespace base
diff --git a/components/os_crypt/sync/BUILD.gn b/components/os_crypt/sync/BUILD.gn
index 4fe7a0bfaa5b3398372f55c6454e738f140efe6b..b1c70281c45aaca4ae483f1f28e9d21929d17815 100644
--- a/components/os_crypt/sync/BUILD.gn
+++ b/components/os_crypt/sync/BUILD.gn
@@ -46,6 +46,7 @@ component("os_crypt") {
       "os_crypt_mac.mm",
     ]
     deps += [ "//crypto:mock_apple_keychain" ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_win) {
diff --git a/components/remote_cocoa/app_shim/BUILD.gn b/components/remote_cocoa/app_shim/BUILD.gn
index a5815d7c1cab4795dbaf20bfd152810cb78ce0a9..5bb13f382e08f66ed3cb8cd67512b86767e7368a 100644
--- a/components/remote_cocoa/app_shim/BUILD.gn
+++ b/components/remote_cocoa/app_shim/BUILD.gn
@@ -16,6 +16,7 @@ component("app_shim") {
   assert(is_mac)
 
   configs += [ ":app_shim_warnings" ]
+  configs += ["//electron/build/config:mas_build"]
   sources = [
     "alert.h",
     "alert.mm",
diff --git a/components/remote_cocoa/app_shim/application_bridge.mm b/components/remote_cocoa/app_shim/application_bridge.mm
index 5a096477c123a782341115f964c4975301ccaf9a..ecfbb3b405425af346a6ba6788fc1d8ff89760cd 100644
--- a/components/remote_cocoa/app_shim/application_bridge.mm
+++ b/components/remote_cocoa/app_shim/application_bridge.mm
@@ -51,6 +51,7 @@
 
   // NativeWidgetNSWindowHostHelper:
   id GetNativeViewAccessible() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       int64_t browser_pid = 0;
       std::vector<uint8_t> element_token;
@@ -61,6 +62,9 @@ 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 +103,9 @@ 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 53553a707a646012c50b0bd2d0ffd8d4dbd67e11..e9df78b2cf8ca8cb4cb8321769e9a56b96d368b6 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
@@ -9,6 +9,7 @@
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
 
+#if !IS_MAS_BUILD()
 @interface NSWindow (PrivateBrowserNativeWidgetAPI)
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle;
 @end
@@ -65,10 +66,13 @@ - (BOOL)_shouldCenterTrafficLights {
 
 @end
 
+#endif  // MAS_BUILD
+
 @implementation BrowserNativeWidgetWindow
 
 // 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])
@@ -115,6 +119,8 @@ - (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.
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..dbbebbdc1735bc14224dfcde0b7fe3a6fd9f9e40 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 +4,8 @@
 
 #import "components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.h"
 
+#if !IS_MAS_BUILD()
+
 @interface NSWindow (PrivateAPI)
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle;
 @end
@@ -18,8 +20,12 @@ - (CGFloat)_titlebarHeight {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacFramelessNSWindow
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   if ([NativeWidgetMacFramelessNSWindowFrame class]) {
     return [NativeWidgetMacFramelessNSWindowFrame class];
@@ -27,4 +33,6 @@ + (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 25672be4a7dac9a8cd53498184f537292e14d5c2..ef0844ae2845990832fc9777eade94550fb8ffaa 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
@@ -17,6 +17,7 @@ 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 +34,7 @@ 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 4c60785c1998677abc8845c087f672f51dc2ce8f..4c06d59cefb630a2cf7f79f1b41bd8a53ae84643 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
@@ -104,7 +104,9 @@ void OrderChildWindow(NSWindow* child_window,
 }  // namespace
 
 @interface NSWindow (Private)
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle;
+#endif
 - (BOOL)hasKeyAppearance;
 - (long long)_resizeDirectionForMouseLocation:(CGPoint)location;
 - (BOOL)_isConsideredOpenForPersistentState;
@@ -143,6 +145,8 @@ - (void)cr_mouseDownOnFrameView:(NSEvent*)event {
 }
 @end
 
+#if !IS_MAS_BUILD()
+
 @implementation NativeWidgetMacNSWindowTitledFrame
 - (void)mouseDown:(NSEvent*)event {
   if (self.window.isMovable)
@@ -169,6 +173,8 @@ - (BOOL)usesCustomDrawing {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacNSWindow {
  @private
   CommandDispatcher* __strong _commandDispatcher;
@@ -357,6 +363,8 @@ - (NSAccessibilityRole)accessibilityRole {
 
 // NSWindow overrides.
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   if (windowStyle & NSWindowStyleMaskTitled) {
     if (Class customFrame = [NativeWidgetMacNSWindowTitledFrame class])
@@ -368,6 +376,8 @@ + (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 fbc23284b997d80c31f6fb62d8de7fc3076b3195..2d264b95ef73d243fedfe12a24fb4c665805e630 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
@@ -601,10 +601,12 @@ 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 5756139efd53eb9ec6e74007fc10d9f7dfe51d44..8faf652dee5720e066b6ab5f2d4997ee31bfbf1a 100644
--- a/components/viz/service/BUILD.gn
+++ b/components/viz/service/BUILD.gn
@@ -356,6 +356,7 @@ viz_component("service") {
         "frame_sinks/external_begin_frame_source_mac.h",
       ]
     }
+    configs = ["//electron/build/config:mas_build"]
   }
 
   if (is_android || use_ozone) {
@@ -622,6 +623,7 @@ viz_source_set("unit_tests") {
       "display_embedder/software_output_device_mac_unittest.mm",
     ]
     frameworks = [ "IOSurface.framework" ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   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 b15bca430f99aaf02733061d986b3ea78204e748..6ad3b61e20361a68f8d799b5826b0ff303d98b69 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
@@ -90,8 +90,10 @@ 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 content::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 5f6e5b078672c0336cee72300a7a37d6284db226..76650bac392c650946636cedc2f5d9c35ca113fa 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
@@ -2014,15 +2014,21 @@ - (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 64d7c47759e9c7899aaf1c513d0b1b8ee6d97f98..6f885f7ea451310cca7c7686548cd3467984874f 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -54,6 +54,7 @@ source_set("browser") {
     "//content:content_implementation",
     "//v8:external_startup_data",
   ]
+  configs += ["//electron/build/config:mas_build"]
   defines = []
   libs = []
   frameworks = []
diff --git a/content/browser/accessibility/browser_accessibility_manager_mac.mm b/content/browser/accessibility/browser_accessibility_manager_mac.mm
index ce3623bd6353674fee92ba1c36eeda8da8906882..62746522bf5f398b12a8cee35f49bb4fc3b51b53 100644
--- a/content/browser/accessibility/browser_accessibility_manager_mac.mm
+++ b/content/browser/accessibility/browser_accessibility_manager_mac.mm
@@ -21,7 +21,9 @@
 #include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
 #include "ui/accessibility/ax_role_properties.h"
 #include "ui/accessibility/platform/ax_private_webkit_constants_mac.h"
+#if !IS_MAS_BUILD()
 #include "ui/base/cocoa/remote_accessibility_api.h"
+#endif
 
 namespace {
 
@@ -225,6 +227,7 @@ void PostAnnouncementNotification(NSString* announcement,
         return;
       }
 
+#if !IS_MAS_BUILD()
       BrowserAccessibilityManager* root_manager = GetManagerForRootFrame();
       if (root_manager) {
         BrowserAccessibilityManagerMac* root_manager_mac =
@@ -247,6 +250,7 @@ void PostAnnouncementNotification(NSString* announcement,
           return;
         }
       }
+#endif
 
       // Use native VoiceOver support for live regions.
       BrowserAccessibilityCocoa* retained_node = native_node;
@@ -633,6 +637,7 @@ 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
@@ -661,6 +666,7 @@ void PostAnnouncementNotification(NSString* announcement,
   if ([window isKindOfClass:[NSAccessibilityRemoteUIElement class]]) {
     return true;
   }
+#endif
 
   return false;
 }
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 032a1da13d5f75e3b31aa868c5ff138f88c2eed2..2a190ba1e4fed6fa11ddfbf167aac2196dd16d86 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -49,7 +49,9 @@ class ScopedPasswordInputEnabler;
 
 @protocol RenderWidgetHostViewMacDelegate;
 
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class RenderWidgetHostViewCocoa;
 @class CursorAccessibilityScaleFactorObserver;
 
@@ -678,9 +680,11 @@ 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 947af40d33f81c47ad7c3fa0ebcf3a45b697b530..e0fa7a8edcd3a71784d35cb3f18d0b2b8d77c816 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -272,8 +272,10 @@
 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.
@@ -1649,8 +1651,10 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 
 gfx::NativeViewAccessible
 RenderWidgetHostViewMac::AccessibilityGetNativeViewAccessibleForWindow() {
+#if !IS_MAS_BUILD()
   if (remote_window_accessible_)
     return remote_window_accessible_;
+#endif
   return [GetInProcessNSView() window];
 }
 
@@ -1695,9 +1699,11 @@ 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(
@@ -2204,12 +2210,14 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 
 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 250d68fe80384f4409e91dd94a37ebc6ad34d383..4f5f1021dcdf2ca45531b8f56fed44b4c1097e8f 100644
--- a/content/common/BUILD.gn
+++ b/content/common/BUILD.gn
@@ -240,6 +240,7 @@ source_set("common") {
     "//content:content_implementation",
     "//build/config:precompiled_headers",
   ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [
     ":mojo_bindings",
diff --git a/content/renderer/BUILD.gn b/content/renderer/BUILD.gn
index 6fae0b5280d5e5220f4e8695cb898a44de9dd22e..5dc89a6b06799e05051af025985964be4e2c9260 100644
--- a/content/renderer/BUILD.gn
+++ b/content/renderer/BUILD.gn
@@ -227,6 +227,7 @@ target(link_target_type, "renderer") {
   }
 
   configs += [ "//content:content_implementation" ]
+  configs += ["//electron/build/config:mas_build"]
   defines = []
 
   public_deps = [
diff --git a/content/renderer/renderer_main_platform_delegate_mac.mm b/content/renderer/renderer_main_platform_delegate_mac.mm
index d4db3b179725cb96bcbd0f73db7d52ef8b7522db..6afbf1defb0591d9fe59a81e6c74746d3e15f081 100644
--- a/content/renderer/renderer_main_platform_delegate_mac.mm
+++ b/content/renderer/renderer_main_platform_delegate_mac.mm
@@ -10,9 +10,11 @@
 #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 +24,7 @@
 // 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 +33,7 @@ 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 a119b4439bfb9218c7aaf09dca8e78527da7f20d..faa813b003940280c6eeb87e70173019bdd5280c 100644
--- a/content/renderer/theme_helper_mac.mm
+++ b/content/renderer/theme_helper_mac.mm
@@ -8,10 +8,11 @@
 
 #include "base/strings/sys_string_conversions.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CGFontRenderingGetFontSmoothingDisabled(void);
 }
-
+#endif
 namespace content {
 
 void SystemColorsDidChange(int aqua_color_variant) {
@@ -24,8 +25,18 @@ void SystemColorsDidChange(int aqua_color_variant) {
 }
 
 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 8d0a789cccacc4d6a54d9bc499c606f076a3d3b6..0c9dc99d03928defceaae741d588d292301b6ba8 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -479,6 +479,7 @@ static_library("test_support") {
   configs += [
     "//build/config:precompiled_headers",
     "//v8:external_startup_data",
+    "//electron/build/config:mas_build",
   ]
 
   public_deps = [
@@ -1075,6 +1076,7 @@ static_library("browsertest_support") {
   }
 
   configs += [ "//v8:external_startup_data" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 mojom("content_test_mojo_bindings") {
@@ -1690,6 +1692,7 @@ test("content_browsertests") {
   defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
 
   configs += [ "//build/config:precompiled_headers" ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [
     ":test_interfaces",
@@ -2932,6 +2935,7 @@ test("content_unittests") {
   }
 
   configs += [ "//build/config:precompiled_headers" ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [ "//content:content_resources" ]
 
diff --git a/content/web_test/BUILD.gn b/content/web_test/BUILD.gn
index 24facc48c2b6b30db3a7cb36e4222019b471e84b..d1d3e72407682b01e6c2173cd34445dbc44cb86d 100644
--- a/content/web_test/BUILD.gn
+++ b/content/web_test/BUILD.gn
@@ -149,6 +149,8 @@ static_library("web_test_browser") {
     "browser/web_test_tts_platform.h",
   ]
 
+  configs += ["//electron/build/config:mas_build"]
+
   if (is_mac) {
     sources += [ "browser/web_test_shell_platform_delegate_mac.mm" ]
   } else if (toolkit_views && !is_castos) {
diff --git a/device/bluetooth/BUILD.gn b/device/bluetooth/BUILD.gn
index e09b425de7f7c799f675d385d6a8189baaeb13dd..3ddb0afe42879933c7a15c1bb82309736e78a15a 100644
--- a/device/bluetooth/BUILD.gn
+++ b/device/bluetooth/BUILD.gn
@@ -243,6 +243,7 @@ component("bluetooth") {
       "IOKit.framework",
       "Foundation.framework",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_mac) {
diff --git a/device/bluetooth/bluetooth_adapter_mac.mm b/device/bluetooth/bluetooth_adapter_mac.mm
index 3033b23a07041d375d5733bad1901f9a61bdf3b6..9dd6cb1aa49d03c167d1a92100d4ba5f08f93abe 100644
--- a/device/bluetooth/bluetooth_adapter_mac.mm
+++ b/device/bluetooth/bluetooth_adapter_mac.mm
@@ -37,6 +37,7 @@
 #include "device/bluetooth/bluetooth_socket_mac.h"
 #include "device/bluetooth/public/cpp/bluetooth_address.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
@@ -50,6 +51,7 @@
 // [4] https://support.apple.com/kb/PH25091
 void IOBluetoothPreferenceSetControllerPowerState(int state);
 }
+#endif
 
 namespace {
 
@@ -93,8 +95,10 @@ 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)) {
 }
@@ -242,8 +246,12 @@ 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 e321b406a8375986b41d64342919bb0e8c5e58eb..8081d53adab80a6fccfdb4cd6f608c3bf7112c47 100644
--- a/gpu/ipc/service/BUILD.gn
+++ b/gpu/ipc/service/BUILD.gn
@@ -133,6 +133,7 @@ component("service") {
       "QuartzCore.framework",
     ]
     defines += [ "GL_SILENCE_DEPRECATION" ]
+    configs += ["//electron/build/config:mas_build"]
   }
   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 b994079339dc0aebd86dac807645f81c2974fb96..b05e35c8eabccfd3147030d03453d78e76cdc5d2 100644
--- a/gpu/ipc/service/image_transport_surface_overlay_mac.h
+++ b/gpu/ipc/service/image_transport_surface_overlay_mac.h
@@ -23,7 +23,9 @@
 #include "ui/display/types/display_constants.h"
 #endif
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 
 namespace ui {
@@ -76,8 +78,10 @@ class ImageTransportSurfaceOverlayMacEGL : public gl::Presenter {
                        const gfx::PresentationFeedback& feedback);
   void PopulateCALayerParameters();
 
+#if !IS_MAS_BUILD()
   const bool use_remote_layer_api_;
   CAContext* __strong ca_context_;
+#endif
   std::unique_ptr<ui::CALayerTreeCoordinator> ca_layer_tree_coordinator_;
 
   gfx::Size pixel_size_;
diff --git a/gpu/ipc/service/image_transport_surface_overlay_mac.mm b/gpu/ipc/service/image_transport_surface_overlay_mac.mm
index 3af7bb0fddf848f3c76d14c24730c6aba07fd83e..b23f152143d4958b7492cae47b8a3b01992e235f 100644
--- a/gpu/ipc/service/image_transport_surface_overlay_mac.mm
+++ b/gpu/ipc/service/image_transport_surface_overlay_mac.mm
@@ -75,12 +75,16 @@
 }  // namespace
 
 ImageTransportSurfaceOverlayMacEGL::ImageTransportSurfaceOverlayMacEGL()
-    : use_remote_layer_api_(ui::RemoteLayerAPISupported()),
+    :
+#if !IS_MAS_BUILD()
+    use_remote_layer_api_(ui::RemoteLayerAPISupported()),
+#endif
       scale_factor_(1),
       weak_ptr_factory_(this) {
   static bool av_disabled_at_command_line =
       !base::FeatureList::IsEnabled(kAVFoundationOverlays);
 
+#if !IS_MAS_BUILD()
   ca_layer_tree_coordinator_ = std::make_unique<ui::CALayerTreeCoordinator>(
       use_remote_layer_api_, !av_disabled_at_command_line);
 
@@ -101,6 +105,10 @@
 #endif
     ca_context_.layer = ca_layer_tree_coordinator_->GetCALayerForDisplay();
   }
+#else
+  ca_layer_tree_coordinator_ = std::make_unique<ui::CALayerTreeCoordinator>(
+      /*allow_remote_layers=*/false, !av_disabled_at_command_line);
+#endif
 }
 
 ImageTransportSurfaceOverlayMacEGL::~ImageTransportSurfaceOverlayMacEGL() {
@@ -233,9 +241,13 @@
     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 (use_remote_layer_api_) {
       params.ca_context_id = [ca_context_ contextId];
     } else {
+#else
+    if (true) {
+#endif
       IOSurfaceRef io_surface =
           ca_layer_tree_coordinator_->GetIOSurfaceForDisplay();
       if (io_surface) {
diff --git a/media/audio/BUILD.gn b/media/audio/BUILD.gn
index 90e093cd2d499ba0f37f3246bab288c758b51e19..6027134a4de53e6fe39fdbfdb67885e0b5f56e40 100644
--- a/media/audio/BUILD.gn
+++ b/media/audio/BUILD.gn
@@ -199,6 +199,7 @@ source_set("audio") {
       "CoreMedia.framework",
     ]
     weak_frameworks = [ "ScreenCaptureKit.framework" ]  # macOS 13.0
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_ios) {
diff --git a/media/audio/apple/audio_low_latency_input.cc b/media/audio/apple/audio_low_latency_input.cc
index 8cd474c33e514fd0aa90daf68a56ed7fc902d713..9fff9cc7b00b257c3bebb02c75a3c2e809ffdf0a 100644
--- a/media/audio/apple/audio_low_latency_input.cc
+++ b/media/audio/apple/audio_low_latency_input.cc
@@ -33,19 +33,23 @@
 
 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/media/audio/mac/audio_manager_mac.cc b/media/audio/mac/audio_manager_mac.cc
index ac44f991c6cbe464d8867d8b3c77e1a5082793a7..7933a70a4b88b3cd00724aa025e82aecd867a5f3 100644
--- a/media/audio/mac/audio_manager_mac.cc
+++ b/media/audio/mac/audio_manager_mac.cc
@@ -969,7 +969,7 @@ AudioParameters AudioManagerMac::GetPreferredOutputStreamParameters(
 
 void AudioManagerMac::InitializeOnAudioThread() {
   DCHECK(GetTaskRunner()->BelongsToCurrentThread());
-  InitializeCoreAudioDispatchOverride();
+  // InitializeCoreAudioDispatchOverride();
   power_observer_ = std::make_unique<AudioPowerObserver>();
 }
 
diff --git a/net/dns/BUILD.gn b/net/dns/BUILD.gn
index 0c5cb82b1248997ef3b97f17bef52f880fed26fd..8adecabe9aee119c7474834c038c79b271ad888e 100644
--- a/net/dns/BUILD.gn
+++ b/net/dns/BUILD.gn
@@ -183,6 +183,8 @@ source_set("dns") {
     ":host_resolver_manager",
     ":mdns_client",
   ]
+
+  configs += ["//electron/build/config:mas_build"]
 }
 
 # 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 04c2079aac882cb2913583d4692302fdf564a74d..2a03be8bb4b089473e61601323646d257da5e39e 100644
--- a/net/dns/dns_config_service_posix.cc
+++ b/net/dns/dns_config_service_posix.cc
@@ -130,8 +130,8 @@ 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.";
@@ -148,6 +148,7 @@ 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 299a028f23314f479d2da8f914a5bdf34698d854..672dcb04dd3cf4e3cc71403f727a1dde91ad4402 100644
--- a/sandbox/mac/BUILD.gn
+++ b/sandbox/mac/BUILD.gn
@@ -39,6 +39,7 @@ component("seatbelt") {
   ]
   public_deps = [ "//third_party/protobuf:protobuf_lite" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 component("seatbelt_extension") {
@@ -52,6 +53,7 @@ component("seatbelt_extension") {
   libs = [ "sandbox" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 component("system_services") {
@@ -66,6 +68,7 @@ component("system_services") {
   deps = [ ":seatbelt_export" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  configs += ["//electron/build/config:mas_build"]
 }
 
 source_set("sandbox_unittests") {
diff --git a/sandbox/mac/sandbox_compiler.cc b/sandbox/mac/sandbox_compiler.cc
index f35d9ef2a2df3db8ecbf1d7b909c7b1cf33f3cd9..a710b8b4f851666fd65bb37f69ec2fa70259697b 100644
--- a/sandbox/mac/sandbox_compiler.cc
+++ b/sandbox/mac/sandbox_compiler.cc
@@ -47,6 +47,7 @@ bool SandboxCompiler::SetParameter(const std::string& key,
 }
 
 bool SandboxCompiler::CompileAndApplyProfile(std::string& error) {
+#if !IS_MAS_BUILD()
   if (mode_ == Target::kSource) {
     std::vector<const char*> params;
 
@@ -67,6 +68,9 @@ bool SandboxCompiler::CompileAndApplyProfile(std::string& error) {
     }
   }
   return false;
+#else
+  return true;
+#endif
 }
 
 bool SandboxCompiler::CompilePolicyToProto(mac::SandboxPolicy& policy,
diff --git a/sandbox/mac/sandbox_logging.cc b/sandbox/mac/sandbox_logging.cc
index 095c639b9893e885d8937e29ed7d47a7c28bc6b6..cfa5e307de8326fbc335996feaf9595d1572cd3d 100644
--- a/sandbox/mac/sandbox_logging.cc
+++ b/sandbox/mac/sandbox_logging.cc
@@ -33,9 +33,11 @@
   }
 #endif
 
+#if !IS_MAS_BUILD()
 extern "C" {
 void abort_report_np(const char*, ...);
 }
+#endif
 
 namespace sandbox::logging {
 
@@ -76,9 +78,11 @@ 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/seatbelt.cc b/sandbox/mac/seatbelt.cc
index 15c835e118456394c0a00ac98c11241c14ca75bd..83759e5fbc252fa57ca2fa122873dfac3d61d46d 100644
--- a/sandbox/mac/seatbelt.cc
+++ b/sandbox/mac/seatbelt.cc
@@ -9,7 +9,7 @@
 
 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 +40,13 @@ 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 +74,48 @@ 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 +126,7 @@ 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 +135,9 @@ 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
@@ -129,10 +145,14 @@ bool Seatbelt::InitWithParams(const char* profile,
                               uint64_t flags,
                               const char* const parameters[],
                               std::string* error) {
+#if !IS_MAS_BUILD()
   char* errorbuf = nullptr;
   int rv =
       ::sandbox_init_with_parameters(profile, flags, parameters, &errorbuf);
   return HandleSandboxResult(rv, errorbuf, error);
+#else
+  return true;
+#endif
 }
 
 // static
@@ -140,6 +160,7 @@ 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);
@@ -149,33 +170,44 @@ 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 18479382a277cb2b25626ec8d31442bfd1377ee6..7d80d7fa8337523c3a70f317f883f0cc26c6f40b 100644
--- a/sandbox/mac/seatbelt_extension.cc
+++ b/sandbox/mac/seatbelt_extension.cc
@@ -11,6 +11,7 @@
 #include "base/notreached.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 +23,7 @@ char* sandbox_extension_issue_file(const char* type,
                                    const char* path,
                                    uint32_t flags);
 }
+#endif
 
 namespace sandbox {
 
@@ -50,7 +52,11 @@ 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 +68,11 @@ 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 +90,14 @@ 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();
       return nullptr;
diff --git a/sandbox/mac/system_services.cc b/sandbox/mac/system_services.cc
index eb81a70e4d5d5cd3e6ae9b45f8cd1c795ea76c51..dc30306f2c5d20503399fc3a8860773aa0044352 100644
--- a/sandbox/mac/system_services.cc
+++ b/sandbox/mac/system_services.cc
@@ -9,6 +9,7 @@
 
 #include "base/apple/osstatus_logging.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 OSStatus SetApplicationIsDaemon(Boolean isDaemon);
 void _LSSetApplicationLaunchServicesServerConnectionStatus(
@@ -19,10 +20,12 @@ 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 +39,13 @@ 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 421b11f8839a7304b0dd8a976b9f2176832c32bc..7738b5a04fb020681dfdd03dae5ac4331db08e4a 100644
--- a/third_party/blink/renderer/core/BUILD.gn
+++ b/third_party/blink/renderer/core/BUILD.gn
@@ -312,6 +312,7 @@ component("core") {
   configs -= core_config_remove
   configs += core_config_add
   configs += [ "//v8:external_startup_data" ]
+  configs += ["//electron/build/config:mas_build"]
 
   public_deps = [
     ":core_generated",
diff --git a/third_party/blink/renderer/core/editing/build.gni b/third_party/blink/renderer/core/editing/build.gni
index 16bc33b36fa860214a6b4647d69939080df1b556..3c170e36fbeaddee2790f79039d81c0ef958572f 100644
--- a/third_party/blink/renderer/core/editing/build.gni
+++ b/third_party/blink/renderer/core/editing/build.gni
@@ -354,10 +354,14 @@ 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 3ead42e14ad9d41a30c5637678a3ac49296ce2a6..8dec61ee6a62e54ec3c8c5dd5e08601c28d04dfe 100644
--- a/ui/accelerated_widget_mac/BUILD.gn
+++ b/ui/accelerated_widget_mac/BUILD.gn
@@ -33,6 +33,8 @@ component("accelerated_widget_mac") {
     "QuartzCore.framework",
   ]
 
+  configs += ["//electron/build/config:mas_build"]
+
   if (is_ios) {
     sources += [ "ca_layer_frame_sink_provider.h" ]
   }
diff --git a/ui/accelerated_widget_mac/display_ca_layer_tree.mm b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
index dcf493d62990018040a3f84b6f875af737bd2214..6ffffe8b3946e0427aead8be19878c537c841294 100644
--- a/ui/accelerated_widget_mac/display_ca_layer_tree.mm
+++ b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
@@ -121,6 +121,7 @@ - (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 +151,9 @@ - (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 fc99800e70eb29b94ac356b55caef81a25518896..e9fe9be7f737372b0111e113bd120b520fb4568a 100644
--- a/ui/accessibility/platform/BUILD.gn
+++ b/ui/accessibility/platform/BUILD.gn
@@ -254,6 +254,7 @@ component("platform") {
       weak_frameworks = [
         "Accessibility.framework",  # macOS 11
       ]
+      configs += ["//electron/build/config:mas_build"]
     }
 
     if (use_atk) {
diff --git a/ui/accessibility/platform/inspect/ax_transform_mac.mm b/ui/accessibility/platform/inspect/ax_transform_mac.mm
index c737a2ca1afb44083aef33c6aa4518bea68d1aba..879f1357b5129849c5a1aa1731cf769712569e9e 100644
--- a/ui/accessibility/platform/inspect/ax_transform_mac.mm
+++ b/ui/accessibility/platform/inspect/ax_transform_mac.mm
@@ -108,6 +108,7 @@
     }
   }
 
+#if !IS_MAS_BUILD()
   // AXTextMarker
   if (IsAXTextMarker(value)) {
     return AXTextMarkerToBaseValue(value, indexer);
@@ -117,6 +118,7 @@
   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 3452178f0db87d7d18af3fea5386dc56b85e7fd2..fa510698a6ccc1c3d0e800733d69e167364b1663 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -361,6 +361,7 @@ component("base") {
       "interaction/element_tracker_mac.mm",
       "resource/resource_bundle_mac.mm",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_apple) {
@@ -378,6 +379,13 @@ component("base") {
     sources += [ "resource/resource_bundle_lacros.cc" ]
   }
 
+  if (is_mas_build) {
+    sources -= [
+      "cocoa/remote_accessibility_api.h",
+      "cocoa/remote_accessibility_api.mm",
+    ]
+  }
+
   if (is_ios) {
     sources += [
       "device_form_factor_ios.mm",
diff --git a/ui/base/cocoa/remote_accessibility_api.h b/ui/base/cocoa/remote_accessibility_api.h
index 3182458838aa96d34911280ab4c6c3aa4aa22d6d..17b57f54492421743a0d69106eefce2c9beb8e87 100644
--- a/ui/base/cocoa/remote_accessibility_api.h
+++ b/ui/base/cocoa/remote_accessibility_api.h
@@ -13,6 +13,8 @@
 
 // NSAccessibilityRemoteUIElement is a private class in AppKit.
 
+#if !IS_MAS_BUILD()
+
 @interface NSAccessibilityRemoteUIElement : NSObject
 + (void)setRemoteUIApp:(BOOL)flag;
 + (BOOL)isRemoteUIApp;
@@ -38,4 +40,6 @@ 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..d585ba14b34021a93c878d0d9f9d9ef70eed32ca 100644
--- a/ui/base/cocoa/remote_layer_api.h
+++ b/ui/base/cocoa/remote_layer_api.h
@@ -17,6 +17,7 @@
 
 #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 +69,8 @@ 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..962df2d65d61ec0836cf465d847eb666033846f2 100644
--- a/ui/base/cocoa/remote_layer_api.mm
+++ b/ui/base/cocoa/remote_layer_api.mm
@@ -10,6 +10,7 @@
 
 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 +18,10 @@
              "RemoteCoreAnimationAPI",
              base::FEATURE_ENABLED_BY_DEFAULT);
 }  // namespace
+#endif
 
 bool RemoteLayerAPISupported() {
+#if !IS_MAS_BUILD()
   if (!base::FeatureList::IsEnabled(kRemoteCoreAnimationAPI))
     return false;
 
@@ -55,6 +58,9 @@ 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 fb806dddc33f8dc880ae5fdefb9389bf38a18931..3d8c09b5deed91b1381793578e17afe2750bc3ee 100644
--- a/ui/display/BUILD.gn
+++ b/ui/display/BUILD.gn
@@ -69,6 +69,10 @@ component("display") {
       "mac/display_link_mac.h",
       "mac/screen_mac.mm",
     ]
+
+    configs += [
+      "//electron/build/config:mas_build"
+    ]
   }
 
   if (is_win) {
diff --git a/ui/display/mac/screen_mac.mm b/ui/display/mac/screen_mac.mm
index a771c1c03fd1afe3a5e563b4421721a5ddc2eb93..a6cbdfcbeff30508d921d4637aac543dce9e8ad3 100644
--- a/ui/display/mac/screen_mac.mm
+++ b/ui/display/mac/screen_mac.mm
@@ -171,7 +171,17 @@ 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.
   {
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index 3702eefa91a9dd22752b3d06d531885928a4d7a6..a78fd474d63d709a703f9c530c687305ddebcea0 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -204,6 +204,7 @@ component("gfx") {
       "scoped_ns_graphics_context_save_gstate_mac.h",
       "scoped_ns_graphics_context_save_gstate_mac.mm",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
   if (is_win) {
     sources += [
diff --git a/ui/gfx/platform_font_mac.mm b/ui/gfx/platform_font_mac.mm
index 0ab5fbd2a81d8860c73f29c08896f6755b5ca5fa..9400c6c7698258ff2834c550fb8901b49ced35bd 100644
--- a/ui/gfx/platform_font_mac.mm
+++ b/ui/gfx/platform_font_mac.mm
@@ -28,9 +28,11 @@
 
 using Weight = Font::Weight;
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CTFontDescriptorIsSystemUIFont(CTFontDescriptorRef);
 }
+#endif
 
 namespace {
 
@@ -245,7 +247,13 @@ CTFontRef SystemFontForConstructorOfType(PlatformFontMac::SystemFontType type) {
   // 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 a64df51a061e4d1b1d923fab830e5b3be4c389ba..e0cb6abb7a5010c69f82a3edcea5700cda3895cf 100644
--- a/ui/views/BUILD.gn
+++ b/ui/views/BUILD.gn
@@ -710,6 +710,7 @@ component("views") {
       "IOSurface.framework",
       "QuartzCore.framework",
     ]
+    configs += ["//electron/build/config:mas_build"]
   }
 
   if (is_win) {
@@ -1139,6 +1140,8 @@ source_set("test_support") {
     "//testing/gtest",
   ]
 
+  configs += ["//electron/build/config:mas_build"]
+
   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 f37c02488e6ba943ebf9b880a04bcfef9afc9d97..b10ed25b5cdf5eb2f314ed72226f71c8bc35e58e 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.h
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.h
@@ -30,7 +30,9 @@
 #include "ui/views/window/dialog_observer.h"
 
 @class NativeWidgetMacNSWindow;
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class NSView;
 
 namespace remote_cocoa {
@@ -465,10 +467,12 @@ 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 52ee42399fdec85ab31da6cf6392698f58c4f2cb..9592cf7eadccbba522661da5a906896f11f69942 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.mm
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
@@ -345,7 +345,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
 NativeWidgetMacNSWindowHost::GetNativeViewAccessibleForNSView() const {
   if (in_process_ns_window_bridge_)
     return in_process_ns_window_bridge_->ns_view();
+#if !IS_MAS_BUILD()
   return remote_view_accessible_;
+#else
+  return nullptr;
+#endif
 }
 
 gfx::NativeViewAccessible
@@ -360,7 +364,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
     return [in_process_ns_window_bridge_->ns_view() window];
   }
 
+#if !IS_MAS_BUILD()
   return remote_window_accessible_;
+#else
+  return nullptr;
+#endif
 }
 
 remote_cocoa::mojom::NativeWidgetNSWindow*
@@ -1410,6 +1418,7 @@ 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_ =
@@ -1421,11 +1430,13 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
       ![NSAccessibilityRemoteUIElement isRemoteUIApp]) {
     [NSAccessibilityRemoteUIElement setRemoteUIApp:YES];
   }
+#endif
 }
 
 bool NativeWidgetMacNSWindowHost::GetRootViewAccessibilityToken(
     int64_t* pid,
     std::vector<uint8_t>* token) {
+#if !IS_MAS_BUILD()
   *pid = getpid();
   id element_id = GetNativeViewAccessible();
 
@@ -1438,6 +1449,7 @@ 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 e3dd4fab3a1cac0138f8dac60247e0ea3343e87e..f31130eaa3719eda0da5b3f0e8c294775faf6bd4 100644
--- a/ui/views/controls/webview/BUILD.gn
+++ b/ui/views/controls/webview/BUILD.gn
@@ -19,6 +19,9 @@ component("webview") {
 
   if (is_mac) {
     sources += [ "unhandled_keyboard_event_handler_mac.mm" ]
+    configs += [
+      "//electron/build/config:mas_build",
+    ]
   }
 
   if (is_win) {