Do not give GPU memory to backgrounded compositors.

cc/test/fake_output_surface_client.h

 // Copyright 2013 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_TEST_FAKE_OUTPUT_SURFACE_CLIENT_H_
 #define CC_TEST_FAKE_OUTPUT_SURFACE_CLIENT_H_
 
 #include "cc/output/managed_memory_policy.h"
 #include "cc/output/output_surface_client.h"
 
 namespace cc {
 
 class FakeOutputSurfaceClient : public OutputSurfaceClient {
  public:
   FakeOutputSurfaceClient()
       : begin_impl_frame_count_(0),
         deferred_initialize_result_(true),
         deferred_initialize_called_(false),
         did_lose_output_surface_called_(false),
-        memory_policy_(0),
-        discard_backbuffer_when_not_visible_(false) {}
+        memory_policy_(0) {}
 
   virtual bool DeferredInitialize(
       scoped_refptr<ContextProvider> offscreen_context_provider) OVERRIDE;
   virtual void ReleaseGL() OVERRIDE {}
   virtual void SetNeedsRedrawRect(gfx::Rect damage_rect) OVERRIDE {}
   virtual void BeginImplFrame(const BeginFrameArgs& args) OVERRIDE;
   virtual void OnSwapBuffersComplete() OVERRIDE {}
   virtual void ReclaimResources(const CompositorFrameAck* ack) OVERRIDE {}
   virtual void DidLoseOutputSurface() OVERRIDE;
   virtual void SetExternalDrawConstraints(
       const gfx::Transform& transform,
       gfx::Rect viewport,
       gfx::Rect clip,
       bool valid_for_tile_management) OVERRIDE {}
   virtual void SetMemoryPolicy(const ManagedMemoryPolicy& policy) OVERRIDE;
-  virtual void SetDiscardBackBufferWhenNotVisible(bool discard) OVERRIDE;
   virtual void SetTreeActivationCallback(const base::Closure&) OVERRIDE {}
 
   int begin_impl_frame_count() {
     return begin_impl_frame_count_;
   }
 
   void set_deferred_initialize_result(bool result) {
     deferred_initialize_result_ = result;
   }
 
   bool deferred_initialize_called() {
     return deferred_initialize_called_;
   }
 
   bool did_lose_output_surface_called() {
     return did_lose_output_surface_called_;
   }
 
   const ManagedMemoryPolicy& memory_policy() const { return memory_policy_; }
 
-  bool discard_backbuffer_when_not_visible() const {
-    return discard_backbuffer_when_not_visible_;
-  }
-
  private:
   int begin_impl_frame_count_;
   bool deferred_initialize_result_;
   bool deferred_initialize_called_;
   bool did_lose_output_surface_called_;
   ManagedMemoryPolicy memory_policy_;
-  bool discard_backbuffer_when_not_visible_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_OUTPUT_SURFACE_CLIENT_H_