Keeping track of descendants that draw content instead of recalcualting

cc/layers/delegated_renderer_layer.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_DELEGATED_RENDERER_LAYER_H_
 #define CC_LAYERS_DELEGATED_RENDERER_LAYER_H_
 
 #include "base/containers/hash_tables.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 14 matching lines @@
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl)
       OVERRIDE;
   virtual void SetLayerTreeHost(LayerTreeHost* host) OVERRIDE;
   virtual bool Update(ResourceUpdateQueue* queue,
                       const OcclusionTracker<Layer>* occlusion) OVERRIDE;
   virtual void PushPropertiesTo(LayerImpl* impl) OVERRIDE;
 
   // Called by the DelegatedFrameProvider when a new frame is available to be
   // picked up.
   void ProviderHasNewFrame();
+  virtual int NumDescendantsThatDrawContent() const OVERRIDE;

[danakj, 2014/07/14 14:57:45]

Oh, instead of this, can we put HasDelegatedContent() on this layer like we have
on DRLImpl instead? The lying about num descendants can come at the place we
compute that instead of here?

[awoloszyn, 2014/07/14 19:38:32]

Done.

 
  protected:
   DelegatedRendererLayer(
       const scoped_refptr<DelegatedFrameProvider>& frame_provider);
   virtual ~DelegatedRendererLayer();
 
  private:
   scoped_refptr<DelegatedFrameProvider> frame_provider_;
 
   bool should_collect_new_frame_;
 
   DelegatedFrameData* frame_data_;
   gfx::RectF frame_damage_;
 
   scoped_refptr<BlockingTaskRunner> main_thread_runner_;
   base::WeakPtrFactory<DelegatedRendererLayer> weak_ptrs_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegatedRendererLayer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_DELEGATED_RENDERER_LAYER_H_