cc: Don't do CompositeAndReadback when using DelegatingRenderer.

cc/output/direct_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_DIRECT_RENDERER_H_
 #define CC_OUTPUT_DIRECT_RENDERER_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/renderer.h"
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/scoped_resource.h"
 
 namespace cc {
 
 class ResourceProvider;
 
 // This is the base class for code shared between the GL and software
 // renderer implementations.  "Direct" refers to the fact that it does not
 // delegate rendering to another compositor.
 class CC_EXPORT DirectRenderer : public Renderer {
  public:
   virtual ~DirectRenderer();
 
   ResourceProvider* resource_provider() const { return resource_provider_; }
 
+  virtual bool CanReadPixels() const OVERRIDE;
   virtual void DecideRenderPassAllocationsForFrame(
       const RenderPassList& render_passes_in_draw_order) OVERRIDE;
   virtual bool HaveCachedResourcesForRenderPassId(RenderPass::Id id) const
       OVERRIDE;
   virtual void DrawFrame(RenderPassList* render_passes_in_draw_order) OVERRIDE;
 
   struct CC_EXPORT DrawingFrame {
     DrawingFrame();
     ~DrawingFrame();
 
@@ skipping 84 matching lines @@
 
  private:
   gfx::Vector2d enlarge_pass_texture_amount_;
 
   DISALLOW_COPY_AND_ASSIGN(DirectRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_DIRECT_RENDERER_H_