Fall back to software mode if Aura can't create a GL context

ui/compositor/test/default_context_factory.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 UI_COMPOSITOR_TEST_DEFAULT_CONTEXT_FACTORY_H_
 #define UI_COMPOSITOR_TEST_DEFAULT_CONTEXT_FACTORY_H_
 
 #include "ui/compositor/compositor.h"
 
 namespace webkit {
 namespace gpu {
 class ContextProviderInProcess;
 }
 }
 
 namespace ui {
 
 // The default factory that creates in-process contexts.
 class DefaultContextFactory : public ContextFactory {
  public:
   DefaultContextFactory();
   virtual ~DefaultContextFactory();
 
   // ContextFactory implementation
   virtual scoped_ptr<cc::OutputSurface> CreateOutputSurface(
-      Compositor* compositor) OVERRIDE;
+      Compositor* compositor, bool software_fallback) OVERRIDE;
 
   virtual scoped_refptr<Reflector> CreateReflector(
       Compositor* compositor,
       Layer* layer) OVERRIDE;
   virtual void RemoveReflector(scoped_refptr<Reflector> reflector) OVERRIDE;
 
   virtual scoped_refptr<cc::ContextProvider>
       OffscreenCompositorContextProvider() OVERRIDE;
   virtual scoped_refptr<cc::ContextProvider>
       SharedMainThreadContextProvider() OVERRIDE;
   virtual void RemoveCompositor(Compositor* compositor) OVERRIDE;
   virtual bool DoesCreateTestContexts() OVERRIDE;
 
   bool Initialize();
 
  private:
   scoped_refptr<webkit::gpu::ContextProviderInProcess>
       offscreen_compositor_contexts_;
   scoped_refptr<webkit::gpu::ContextProviderInProcess>
       shared_main_thread_contexts_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultContextFactory);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_TEST_DEFAULT_CONTEXT_FACTORY_H_