cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/test/test_compositor_frame_sink.cc

Index: cc/test/test_compositor_frame_sink.cc
diff --git a/cc/test/test_compositor_frame_sink.cc b/cc/test/test_compositor_frame_sink.cc
index 2f383c96e50514268455d1995478e574e6a3006c..28163e1f97da244914b082fee7fe4a195e8e8710 100644
--- a/cc/test/test_compositor_frame_sink.cc
+++ b/cc/test/test_compositor_frame_sink.cc
@@ -82,7 +82,7 @@ bool TestCompositorFrameSink::BindToClient(CompositorFrameSinkClient* client) {
                                             renderer_settings_.refresh_rate));
     }
     scheduler.reset(new DisplayScheduler(
-        begin_frame_source.get(), task_runner_.get(),
+        task_runner_.get(),
         display_output_surface->capabilities().max_frames_pending));
   }