color: Set GpuMemoryBuffer color spaces for Canvas

gpu/ipc/common/surface_handle.h

 // Copyright 2016 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 GPU_IPC_COMMON_SURFACE_HANDLE_H_
 #define GPU_IPC_COMMON_SURFACE_HANDLE_H_
 
 #include <stdint.h>
 
 #include "build/build_config.h"
@@ skipping 11 matching lines @@
 
 // On Windows, Linux and Chrome OS, we can use a AcceleratedWidget across
 // processes, so SurfaceHandle is exactly that.
 // On Mac and Android, there is no type we can directly access across processes,
 // so we go through the GpuSurfaceTracker, and SurfaceHandle is a (scalar)
 // handle generated by that.
 // On NaCl, we don't have native surfaces per se, but we need SurfaceHandle to
 // be defined, because some APIs that use it are referenced there.
 #if defined(GPU_SURFACE_HANDLE_IS_ACCELERATED_WINDOW)
 using SurfaceHandle = gfx::AcceleratedWidget;
-const SurfaceHandle kNullSurfaceHandle = gfx::kNullAcceleratedWidget;
+constexpr SurfaceHandle kNullSurfaceHandle = gfx::kNullAcceleratedWidget;

[ccameron, 2016/09/29 20:47:53]

This is not strictly necessary, but it'll be needed if anyone wants to use
gpu::kNullSurfaceHandle in the way that we use gfx::NullAcceleratedWidget here.

 #elif defined(OS_MACOSX) || defined(OS_ANDROID) || defined(OS_NACL)
 using SurfaceHandle = int32_t;
-const SurfaceHandle kNullSurfaceHandle = 0;
+constexpr SurfaceHandle kNullSurfaceHandle = 0;
 #else
 #error Platform not supported.
 #endif
 
 }  // namespace gpu
 
 #endif  // GPU_IPC_COMMON_SURFACE_HANDLE_H_