cc: Return resources to child compositor via a Callback.

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/synchronization/lock.h"
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
 #include "cc/resources/returned_resource.h"
 
 namespace cc {
 
 class DelegatedFrameData;
 class DelegatedRendererLayerClient;
 
 class CC_EXPORT DelegatedRendererLayer : public Layer {
@@ skipping 17 matching lines @@
 
   // Passes ownership of any unused resources that had been given by the child
   // compositor to the given array, so they can be given back to the child.
   void TakeUnusedResourcesForChildCompositor(ReturnedResourceArray* array);
 
  protected:
   explicit DelegatedRendererLayer(DelegatedRendererLayerClient* client);
   virtual ~DelegatedRendererLayer();
 
  private:
+  void ReceiveUnusedResources(const ReturnedResourceArray& unused);
+
   scoped_ptr<DelegatedFrameData> frame_data_;
   gfx::RectF damage_in_frame_;
   gfx::Size frame_size_;
   gfx::Size display_size_;
-  ReturnedResourceArray unused_resources_for_child_compositor_;
 
   DelegatedRendererLayerClient* client_;
   bool needs_filter_context_;
 
+  base::Lock unused_resources_lock_;
+  ReturnedResourceArray unused_resources_for_child_compositor_;
+
   DISALLOW_COPY_AND_ASSIGN(DelegatedRendererLayer);
 };
 
 }  // namespace cc
+
 #endif  // CC_LAYERS_DELEGATED_RENDERER_LAYER_H_