Query the preferred readback config in CopyFromBackingStore

content/browser/media/capture/web_contents_video_capture_device.cc

Index: content/browser/media/capture/web_contents_video_capture_device.cc
diff --git a/content/browser/media/capture/web_contents_video_capture_device.cc b/content/browser/media/capture/web_contents_video_capture_device.cc
index 093703e145c051b790873ae35219ea0e7fab8114..1cf232388850fa13a07c6dd561fa414ac01cbb90 100644
--- a/content/browser/media/capture/web_contents_video_capture_device.cc
+++ b/content/browser/media/capture/web_contents_video_capture_device.cc
@@ -671,7 +671,10 @@ void WebContentsCaptureMachine::Capture(
         fitted_size,  // Size here is a request not always honored.
         base::Bind(&WebContentsCaptureMachine::DidCopyFromBackingStore,
                    weak_ptr_factory_.GetWeakPtr(),
-                   start_time, target, deliver_frame_cb));
+                   start_time,
+                   target,
+                   deliver_frame_cb),
+        SkBitmap::kARGB_8888_Config);
   }
 }