DidBeginTracing   476 cc/layers/layer_impl.h   virtual void DidBeginTracing();
DidBeginTracing   402 cc/layers/picture_layer_impl.cc   pile_->DidBeginTracing();
DidBeginTracing    72 cc/layers/picture_layer_impl.h   virtual void DidBeginTracing() OVERRIDE;
DidBeginTracing   105 cc/resources/picture_pile_impl.h   void DidBeginTracing();
DidBeginTracing  1336 cc/trees/layer_tree_host_impl.cc   layer->DidBeginTracing();