gpu: Pepper3DImageChromium support on ChromeOS.

content/renderer/pepper/ppb_graphics_3d_impl.h

 // Copyright (c) 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 CONTENT_RENDERER_PEPPER_PPB_GRAPHICS_3D_IMPL_H_
 #define CONTENT_RENDERER_PEPPER_PPB_GRAPHICS_3D_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 98 matching lines @@
   // True if context is bound to instance.
   bool bound_to_instance_;
   // True when waiting for compositor to commit our backing texture.
   bool commit_pending_;
 
 #if DCHECK_IS_ON()
   bool lost_context_ = false;
 #endif
 
   bool has_alpha_;
-  bool use_image_chromium_;
+  const bool use_image_chromium_;
   std::unique_ptr<gpu::CommandBufferProxyImpl> command_buffer_;
 
   base::WeakPtrFactory<PPB_Graphics3D_Impl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_Graphics3D_Impl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_PEPPER_PPB_GRAPHICS_3D_IMPL_H_