cc: Make separate interface for BeginFrame ipc from OutputSurface

cc/output/output_surface_unittest.cc

Index: cc/output/output_surface_unittest.cc
diff --git a/cc/output/output_surface_unittest.cc b/cc/output/output_surface_unittest.cc
index aca1d27ccb950f1e5a056051b87cd3a2ed5ef3e6..7dd8536e049684cf0f84d621444ee522beb7ee92 100644
--- a/cc/output/output_surface_unittest.cc
+++ b/cc/output/output_surface_unittest.cc
@@ -44,10 +44,6 @@ class TestOutputSurface : public OutputSurface {
     CommitVSyncParameters(timebase, interval);
   }
 
-  void BeginFrameForTesting() {
-    client_->BeginFrame(CreateExpiredBeginFrameArgsForTesting());
-  }
-
   void DidSwapBuffersForTesting() { client_->DidSwapBuffers(); }
 
   void OnSwapBuffersCompleteForTesting() { client_->DidSwapBuffersComplete(); }