perf: don't wait for thumbnails if they were not requested on macOS

When using the SCK thumbnail capturer, the first refresh has the list of
sources, and the second refresh has the thumbnails. If thumbnails are
not needed, only wait for the first refresh.

Co-authored-by: John Beutner <[email protected]>

shell/browser/api/electron_api_desktop_capturer.cc

@@ -328,8 +328,9 @@ void DesktopCapturer::StartHandling(bool capture_window,
         window_capturer_->SetThumbnailSize(thumbnail_size);
 #if BUILDFLAG(IS_MAC)
         window_capturer_->skip_next_refresh_ =
-            ShouldUseThumbnailCapturerMac(DesktopMediaList::Type::kWindow) ? 2
-                                                                           : 0;
+            ShouldUseThumbnailCapturerMac(DesktopMediaList::Type::kWindow)
+                ? thumbnail_size.IsEmpty() ? 1 : 2
+                : 0;
 #endif
 
         OnceCallback update_callback = base::BindOnce(
@@ -358,8 +359,9 @@ void DesktopCapturer::StartHandling(bool capture_window,
         screen_capturer_->SetThumbnailSize(thumbnail_size);
 #if BUILDFLAG(IS_MAC)
         screen_capturer_->skip_next_refresh_ =
-            ShouldUseThumbnailCapturerMac(DesktopMediaList::Type::kScreen) ? 2
-                                                                           : 0;
+            ShouldUseThumbnailCapturerMac(DesktopMediaList::Type::kScreen)
+                ? thumbnail_size.IsEmpty() ? 1 : 2
+                : 0;
 #endif
 
         OnceCallback update_callback = base::BindOnce(

spec/api-desktop-capturer-spec.ts

@@ -67,6 +67,22 @@ ifdescribe(!process.arch.includes('arm') && process.platform !== 'win32')('deskt
     }
   });
 
+  it('enabling thumbnail should return non-empty images', async () => {
+    const w2 = new BrowserWindow({ show: false, width: 200, height: 200, webPreferences: { contextIsolation: false } });
+    const wShown = once(w2, 'show');
+    w2.show();
+    await wShown;
+
+    const isNonEmpties: boolean[] = (await desktopCapturer.getSources({
+      types: ['window', 'screen'],
+      thumbnailSize: { width: 100, height: 100 }
+    })).map(s => s.thumbnail.constructor.name === 'NativeImage' && !s.thumbnail.isEmpty());
+
+    w2.destroy();
+    expect(isNonEmpties).to.be.an('array').that.is.not.empty();
+    expect(isNonEmpties.every(e => e === true)).to.be.true();
+  });
+
   it('disabling thumbnail should return empty images', async () => {
     const w2 = new BrowserWindow({ show: false, width: 200, height: 200, webPreferences: { contextIsolation: false } });
     const wShown = once(w2, 'show');