Make disable vsync run the renderer independently

content/renderer/gpu/compositor_external_begin_frame_source.cc

Index: content/renderer/gpu/compositor_external_begin_frame_source.cc
diff --git a/content/renderer/gpu/compositor_external_begin_frame_source.cc b/content/renderer/gpu/compositor_external_begin_frame_source.cc
index 0538f47bdb989da90b4d67de9dfaedb65816a859..c3a8cf7d44a4c9b856b78c584f544a6453115cc1 100644
--- a/content/renderer/gpu/compositor_external_begin_frame_source.cc
+++ b/content/renderer/gpu/compositor_external_begin_frame_source.cc
@@ -55,6 +55,10 @@ void CompositorExternalBeginFrameSource::RemoveObserver(
   external_begin_frame_source_.RemoveObserver(obs);
 }
 
+bool CompositorExternalBeginFrameSource::IsThrottled() const {
+  return true;
+}
+
 void CompositorExternalBeginFrameSource::OnNeedsBeginFrames(
     bool needs_begin_frames) {
   Send(new ViewHostMsg_SetNeedsBeginFrames(routing_id_, needs_begin_frames));