fix: paint and flash issues on macOS (#46629)

patches/chromium/.patches

@@ -131,7 +131,7 @@ osr_shared_texture_remove_keyed_mutex_on_win_dxgi.patch
 feat_allow_usage_of_sccontentsharingpicker_on_supported_platforms.patch
 chore_partial_revert_of.patch
 fix_software_compositing_infinite_loop.patch
-fix_add_method_which_disables_headless_mode_on_native_widget.patch
+fix_adjust_headless_mode_handling_in_native_widget.patch
 refactor_unfilter_unresponsive_events.patch
 build_disable_thin_lto_mac.patch
 feat_corner_smoothing_css_rule_and_blink_painting.patch

patches/chromium/fix_adjust_headless_mode_handling_in_native_widget.patch

@@ -1,7 +1,7 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Cezary Kulakowski <cezary@openfin.co>
 Date: Mon, 22 Jul 2024 16:23:13 +0200
-Subject: fix: add method which disables headless mode on native widget
+Subject: fix: adjust headless mode handling in native widget
 
 We need this method as we create window in headless mode and we
 switch it back to normal mode only after inital paint is done in
@@ -9,8 +9,27 @@ order to get some events like WebContents.beginFrameSubscription.
 If we don't set `is_headless_` to false then some child windows
 e.g. autofill popups will be created in headless mode leading to
 ui problems (like dissapearing popup during typing in html's
-input list.
+input list).
 
+We also need to ensure that an initial paint is scheduled when
+the compositor is unsuspended in headles mode.
+
+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 7bda1853d47034c80a4e416b9839e8d18c5a8e2c..e5df49253103c44f01195fa93988753fb163d13e 100644
+--- a/ui/views/cocoa/native_widget_mac_ns_window_host.mm
++++ b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
+@@ -659,9 +659,10 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
+   // case it will never become visible but we want its compositor to produce
+   // frames for screenshooting and screencasting.
+   UpdateCompositorProperties();
+-  layer()->SetVisible(is_visible_);
++  layer()->SetVisible(is_visible_ || is_headless_mode_window_);
+   if (is_visible_ || is_headless_mode_window_) {
+     compositor_->Unsuspend();
++    layer()->SchedulePaint(layer()->bounds());
+   }
+ 
+   // Register the CGWindowID (used to identify this window for video capture)
 diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
 index 4d1c7d95c338b247f7c63315d536fcc7a7e4b637..55bb9b36f8d0894c972c05ba162fd5b41048013d 100644
 --- a/ui/views/widget/widget.h

shell/browser/api/electron_api_browser_window.cc

@@ -47,7 +47,7 @@ BrowserWindow::BrowserWindow(gin::Arguments* args,
   // Copy the show setting to webContents, but only if we don't want to paint
   // when initially hidden
   bool paint_when_initially_hidden = true;
-  options.Get("paintWhenInitiallyHidden", &paint_when_initially_hidden);
+  options.Get(options::kPaintWhenInitiallyHidden, &paint_when_initially_hidden);
   if (!paint_when_initially_hidden) {
     bool show = true;
     options.Get(options::kShow, &show);

shell/browser/native_window_mac.mm

@@ -154,6 +154,9 @@ NativeWindowMac::NativeWindowMac(const gin_helper::Dictionary& options,
   bool hiddenInMissionControl = false;
   options.Get(options::kHiddenInMissionControl, &hiddenInMissionControl);
 
+  bool paint_when_initially_hidden = true;
+  options.Get(options::kPaintWhenInitiallyHidden, &paint_when_initially_hidden);
+
   // The window without titlebar is treated the same with frameless window.
   if (title_bar_style_ != TitleBarStyle::kNormal)
     set_has_frame(false);
@@ -194,8 +197,8 @@ NativeWindowMac::NativeWindowMac(const gin_helper::Dictionary& options,
   params.bounds = bounds;
   params.delegate = this;
   params.type = views::Widget::InitParams::TYPE_WINDOW;
-  // Allow painting before shown, to be later disabled in ElectronNSWindow.
-  params.headless_mode = true;
+  // Possibly allow painting before shown - later disabled in ElectronNSWindow.
+  params.headless_mode = paint_when_initially_hidden;
   if (IsTranslucent()) {
     params.opacity = views::Widget::InitParams::WindowOpacity::kTranslucent;
   }

shell/common/options_switches.h

@@ -33,6 +33,10 @@ inline constexpr std::string_view kMaximizable = "maximizable";
 inline constexpr std::string_view kFullScreenable = "fullscreenable";
 inline constexpr std::string_view kClosable = "closable";
 
+// Whether to paint when the window is initially hidden.
+inline constexpr std::string_view kPaintWhenInitiallyHidden =
+    "paintWhenInitiallyHidden";
+
 // whether to keep the window out of mission control
 inline constexpr std::string_view kHiddenInMissionControl =
     "hiddenInMissionControl";

spec/api-browser-window-spec.ts

@@ -6475,6 +6475,31 @@ describe('BrowserWindow module', () => {
     w.loadFile(path.join(fixtures, 'pages', 'send-after-node.html'));
   });
 
+  // TODO(codebytere): fix on Windows and Linux too
+  ifdescribe(process.platform === 'darwin')('window.webContents initial paint', () => {
+    afterEach(closeAllWindows);
+    it('paints when a window is initially hidden', async () => {
+      const w = new BrowserWindow({ show: false });
+      await w.loadFile(path.join(fixtures, 'pages', 'a.html'));
+
+      const entries = await w.webContents.executeJavaScript(`
+        new Promise((resolve) => {
+          const observer = new PerformanceObserver((performance) => {
+            observer.disconnect();
+            resolve(performance.getEntries());
+          });
+          observer.observe({ entryTypes: ['paint'] });
+        });
+
+        const header = document.createElement('h1');
+        header.innerText = 'Paint me!!';
+        document.getElementById('div').appendChild(header);
+      `);
+
+      expect(JSON.stringify(entries)).to.eq('{}');
+    });
+  });
+
   describe('window.webContents.focus()', () => {
     afterEach(closeAllWindows);
     it('focuses window', async () => {