Implement MusContextFactory::SharedMainThreadContextProvider()

ui/aura/mus/mus_context_factory.h

 // Copyright 2015 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_AURA_MUS_MUS_CONTEXT_FACTORY_H_
 #define UI_AURA_MUS_MUS_CONTEXT_FACTORY_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "cc/output/context_provider.h"
 #include "cc/output/renderer_settings.h"
 #include "cc/surfaces/surface_manager.h"
 #include "services/ui/public/cpp/raster_thread_helper.h"
 #include "services/ui/public/interfaces/window_tree.mojom.h"
 #include "ui/aura/aura_export.h"
 #include "ui/compositor/compositor.h"
 
 namespace gpu {
 class GpuChannelHost;
 }
@@ skipping 27 matching lines @@
   double GetRefreshRate() const override;
   gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() override;
   cc::TaskGraphRunner* GetTaskGraphRunner() override;
   const cc::RendererSettings& GetRendererSettings() const override;
   void AddObserver(ui::ContextFactoryObserver* observer) override {}
   void RemoveObserver(ui::ContextFactoryObserver* observer) override {}
 
   ui::RasterThreadHelper raster_thread_helper_;
   ui::Gpu* gpu_;
   const cc::RendererSettings renderer_settings_;
+  scoped_refptr<cc::ContextProvider> shared_main_thread_context_provider_;
+
   base::WeakPtrFactory<MusContextFactory> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MusContextFactory);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_MUS_CONTEXT_FACTORY_H_