Add a flag to allow renderer to use software compositor when GL compositor doesn't work.

cc/test/fake_layer_tree_host_client.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_TEST_FAKE_LAYER_TREE_HOST_CLIENT_H_
 #define CC_TEST_FAKE_LAYER_TREE_HOST_CLIENT_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/input/input_handler.h"
 #include "cc/test/fake_context_provider.h"
@@ skipping 13 matching lines @@
   explicit FakeLayerTreeHostClient(RendererOptions options);
   virtual ~FakeLayerTreeHostClient();
 
   virtual void WillBeginFrame() OVERRIDE {}
   virtual void DidBeginFrame() OVERRIDE {}
   virtual void Animate(double frame_begin_time) OVERRIDE {}
   virtual void Layout() OVERRIDE {}
   virtual void ApplyScrollAndScale(gfx::Vector2d scroll_delta,
                                    float page_scale) OVERRIDE {}
 
-  virtual scoped_ptr<OutputSurface> CreateOutputSurface() OVERRIDE;
+  virtual scoped_ptr<OutputSurface> CreateOutputSurface(bool fallback) OVERRIDE;
   virtual void DidInitializeOutputSurface(bool success) OVERRIDE {}
   virtual void WillCommit() OVERRIDE {}
   virtual void DidCommit() OVERRIDE {}
   virtual void DidCommitAndDrawFrame() OVERRIDE {}
   virtual void DidCompleteSwapBuffers() OVERRIDE {}
 
   // Used only in the single-threaded path.
   virtual void ScheduleComposite() OVERRIDE {}
 
   virtual scoped_refptr<cc::ContextProvider>
       OffscreenContextProviderForMainThread() OVERRIDE;
   virtual scoped_refptr<cc::ContextProvider>
       OffscreenContextProviderForCompositorThread() OVERRIDE;
 
  private:
   bool use_software_rendering_;
   bool use_delegating_renderer_;
 
   scoped_refptr<FakeContextProvider> main_thread_contexts_;
   scoped_refptr<FakeContextProvider> compositor_thread_contexts_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_LAYER_TREE_HOST_CLIENT_H_