cc: Implement unified BeginFrame on aura

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 48be5b86003be60ac806e80506a5deda9d131ad6..41a72356978eb708028362f8fa0799dbbbaeb902 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -5283,10 +5283,6 @@ class LayerTreeHostTestSendBeginFramesToChildren : public LayerTreeHostTest {
       : begin_frame_sent_to_children_(false) {
   }
 
-  void InitializeSettings(LayerTreeSettings* settings) override {
-    settings->forward_begin_frames_to_children = true;
-  }
-
   void BeginTest() override {
     // Kick off the test with a commit.
     PostSetNeedsCommitToMainThread();
@@ -5323,7 +5319,6 @@ class LayerTreeHostTestSendBeginFramesToChildrenWithExternalBFS
 
   void InitializeSettings(LayerTreeSettings* settings) override {
     settings->use_external_begin_frame_source = true;
-    settings->forward_begin_frames_to_children = true;
   }
 
   void BeginTest() override {