We should stop using cc::TextureLayer in Canvas2DLayerBridge and DrawingBuffer, and use cc::SurfaceLayer instead.  This will help eliminate a lot of overhead caused by going through the renderer compositor at each animation frame.  It is now possible to synchronize viz::Surface with other surfaces in order to respect the atomicity of display updates that is required by the spec. Therefore, it should be possible to eliminate all uses cc::TextureLayer.