cc: Don't do CompositeAndReadback when using DelegatingRenderer.

cc/output/delegating_renderer.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_OUTPUT_DELEGATING_RENDERER_H_
 #define CC_OUTPUT_DELEGATING_RENDERER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
+#include "cc/output/compositor_frame.h"
 #include "cc/output/renderer.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebGraphicsContext3D.h"
 
 namespace cc {
 
 class OutputSurface;
 class ResourceProvider;
 
 class CC_EXPORT DelegatingRenderer : public Renderer {
  public:
   static scoped_ptr<DelegatingRenderer> Create(
       RendererClient* client,
       OutputSurface* output_surface,
       ResourceProvider* resource_provider);
   virtual ~DelegatingRenderer();
 
   virtual const RendererCapabilities& Capabilities() const OVERRIDE;
 
+  virtual bool CanReadPixels() const OVERRIDE;
+
   virtual void DrawFrame(RenderPassList* render_passes_in_draw_order) OVERRIDE;
 
   virtual void Finish() OVERRIDE {}
 
   virtual void SwapBuffers(const LatencyInfo& latency_info) OVERRIDE;
 
   virtual void GetFramebufferPixels(void* pixels, gfx::Rect rect) OVERRIDE;
 
   virtual void ReceiveCompositorFrameAck(const CompositorFrameAck&) OVERRIDE;
 
   virtual bool IsContextLost() OVERRIDE;
 
   virtual void SetVisible(bool visible) OVERRIDE;
 
   virtual void SendManagedMemoryStats(size_t bytes_visible,
                                       size_t bytes_visible_and_nearby,
                                       size_t bytes_allocated) OVERRIDE {}
 
  private:
   DelegatingRenderer(RendererClient* client,
                      OutputSurface* output_surface,
                      ResourceProvider* resource_provider);
   bool Initialize();
 
   OutputSurface* output_surface_;
   ResourceProvider* resource_provider_;
   RendererCapabilities capabilities_;
+  CompositorFrame frame_for_swap_buffers_;
   bool visible_;
-  RenderPassList render_passes_for_swap_buffers_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegatingRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_DELEGATING_RENDERER_H_