test: add desktopCapturer icon validation (#50261)

* chore: testing of desktopCapturer can run on arm

* fix: DesktopMediaListCaptureThread crash

Fixed a crash when Windows calls ::CoCreateInstance() in the
DesktopMediaListCaptureThread before COM is initialized.

* test: added test for desktopCapturer fetchWindowIcons

* chore: updating Chromium patch hash

---------

Co-authored-by: Charles Kerr <charles@charleskerr.com>

patches/chromium/.patches

@@ -150,3 +150,4 @@ fix_use_fresh_lazynow_for_onendworkitemimpl_after_didruntask.patch
 fix_pulseaudio_stream_and_icon_names.patch
 fix_fire_menu_popup_start_for_dynamically_created_aria_menus.patch
 feat_allow_enabling_extensions_on_custom_protocols.patch
+fix_initialize_com_on_desktopmedialistcapturethread_on_windows.patch

patches/chromium/fix_initialize_com_on_desktopmedialistcapturethread_on_windows.patch

@@ -0,0 +1,32 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Charles Kerr <charles@charleskerr.com>
+Date: Tue, 24 Mar 2026 16:33:20 -0500
+Subject: fix: initialize COM on DesktopMediaListCaptureThread on Windows
+
+On Windows, the DesktopMediaListCaptureThread runs with a UI message
+pump that doesn't initialize COM. When WebRTC's window capturer
+enumerates windows, interacting with UWP/Metro windows causes twinapi.dll
+to internally call ::CoCreateInstance(), which hits Chromium's
+DCheckedCoCreateInstance hook and triggers a crash.
+
+This patch fixes the crash by ensuring COM is initialized on the
+capture thread by calling `init_com_with_mta(false)`.
+
+diff --git a/chrome/browser/media/webrtc/native_desktop_media_list.cc b/chrome/browser/media/webrtc/native_desktop_media_list.cc
+index 9a8ebb4edfb92d9fe28ae4b87463a68547ea1ab3..13446d9849c54f1bfe515c3db4d69dd181ec6d39 100644
+--- a/chrome/browser/media/webrtc/native_desktop_media_list.cc
++++ b/chrome/browser/media/webrtc/native_desktop_media_list.cc
+@@ -786,6 +786,13 @@ NativeDesktopMediaList::NativeDesktopMediaList(
+   base::MessagePumpType thread_type = base::MessagePumpType::UI;
+ #else
+   base::MessagePumpType thread_type = base::MessagePumpType::DEFAULT;
++#endif
++#if BUILDFLAG(IS_WIN)
++  // On Windows, window enumeration via webrtc::DesktopCapturer may interact
++  // with UWP/Metro windows through twinapi.dll, which internally calls
++  // CoCreateInstance. Initialize COM on this thread to prevent crashes in
++  // Chromium's DCheckedCoCreateInstance hook.
++  thread_.init_com_with_mta(false);
+ #endif
+   thread_.StartWithOptions(base::Thread::Options(thread_type, 0));
+ 

spec/api-desktop-capturer-spec.ts

@@ -15,7 +15,7 @@ function getSourceTypes (): ('window' | 'screen')[] {
   return ['window', 'screen'];
 }
 
-ifdescribe(!process.arch.includes('arm') && process.platform !== 'win32')('desktopCapturer', () => {
+describe('desktopCapturer', () => {
   it('should return a non-empty array of sources', async () => {
     const sources = await desktopCapturer.getSources({ types: getSourceTypes() });
     expect(sources).to.be.an('array').that.is.not.empty();
@@ -254,4 +254,61 @@ ifdescribe(!process.arch.includes('arm') && process.platform !== 'win32')('deskt
       destroyWindows();
     }
   });
+
+  // Linux doesn't return any window sources.
+  ifdescribe(process.platform !== 'linux')('fetchWindowIcons', function () {
+    // Tests are sequentially dependent
+    this.bail(true);
+    let w: BrowserWindow;
+    let testSource: Electron.DesktopCapturerSource | undefined;
+    let appIcon: Electron.NativeImage | undefined;
+
+    before(async () => {
+      w = new BrowserWindow({
+        width: 200,
+        height: 200,
+        show: true,
+        title: 'desktop-capturer-test-window'
+      });
+      await w.loadURL('about:blank');
+      const sources = await desktopCapturer.getSources({
+        types: ['window'],
+        fetchWindowIcons: true
+      });
+      testSource = sources.find(
+        s => s.name === 'desktop-capturer-test-window'
+      );
+      appIcon = testSource?.appIcon;
+    });
+
+    after(() => {
+      if (w) w.destroy();
+    });
+
+    it('should find the test window in the list of captured sources', () => {
+      expect(testSource, `The ${w.getTitle()} window was not found by desktopCapturer`).to.exist();
+    });
+
+    it('should return a non-null appIcon for the captured window', () => {
+      expect(appIcon, 'appIcon property is null or undefined').to.exist();
+    });
+
+    it('should return an appIcon that is not an empty image', () => {
+      expect(appIcon?.isEmpty()).to.be.false();
+    });
+
+    it('should return an appIcon that encodes to a valid PNG data URL', () => {
+      const url = appIcon?.toDataURL();
+      expect(url).to.be.a('string');
+      // This is header 'data:image/png;base64,' length;
+      expect(url?.length).to.be.greaterThan(22);
+      expect(url?.startsWith('data:image/png;base64,')).to.be.true();
+    });
+
+    it('should return an appIcon with dimensions greater than 0x0 pixels', () => {
+      const { width, height } = appIcon?.getSize() || { width: 0, height: 0 };
+      expect(width).to.be.greaterThan(0);
+      expect(height).to.be.greaterThan(0);
+    });
+  });
 });