cc: Remove some unnecessary const scoped_refptr&.

cc/surfaces/surface_display_output_surface.h

 // Copyright 2014 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_SURFACES_SURFACE_DISPLAY_OUTPUT_SURFACE_H_
 #define CC_SURFACES_SURFACE_DISPLAY_OUTPUT_SURFACE_H_
 
 #include "base/macros.h"
 #include "cc/output/output_surface.h"
 #include "cc/surfaces/surface_factory.h"
@@ skipping 10 matching lines @@
 // concept, allowing a compositor client to submit frames for a native root
 // window or physical display.
 class CC_SURFACES_EXPORT SurfaceDisplayOutputSurface
     : public OutputSurface,
       public SurfaceFactoryClient {
  public:
   // The underlying Display and SurfaceManager must outlive this class.
   SurfaceDisplayOutputSurface(
       SurfaceManager* surface_manager,
       SurfaceIdAllocator* allocator,
-      const scoped_refptr<ContextProvider>& context_provider,
-      const scoped_refptr<ContextProvider>& worker_context_provider);
+      scoped_refptr<ContextProvider> context_provider,
+      scoped_refptr<ContextProvider> worker_context_provider);
   ~SurfaceDisplayOutputSurface() override;
 
   void set_display_client(OnscreenDisplayClient* display_client) {
     display_client_ = display_client;
   }
   SurfaceFactory* factory() { return &factory_; }
   void ReceivedVSyncParameters(base::TimeTicks timebase,
                                base::TimeDelta interval);
 
   // OutputSurface implementation.
@@ skipping 14 matching lines @@
   gfx::Size display_size_;
   SurfaceId surface_id_;
   SurfaceIdAllocator* allocator_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceDisplayOutputSurface);
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_DISPLAY_OUTPUT_SURFACE_H_