cc, gpu: Use RGBA when using msaa on systems that don't support BGRA

cc/raster/gpu_rasterizer.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 CC_RASTER_GPU_RASTERIZER_H_
 #define CC_RASTER_GPU_RASTERIZER_H_
 
 #include <vector>
 
 #include "cc/base/cc_export.h"
@@ skipping 11 matching lines @@
  public:
   ~GpuRasterizer();
 
   void RasterizeSource(ResourceProvider::ScopedWriteLockGr* write_lock,
                        const RasterSource* raster_source,
                        const gfx::Rect& raster_full_rect,
                        const gfx::Rect& playback_rect,
                        float scale);
 
   ResourceProvider* resource_provider() { return resource_provider_; }
+  int msaa_sample_count() const { return msaa_sample_count_; }
 
  private:
   GpuRasterizer(ContextProvider* context_provider,
                 ResourceProvider* resource_provider,
                 bool use_distance_filed_text,
                 int msaa_sample_count);
 
   ResourceProvider* resource_provider_;
 
   bool use_distance_field_text_;
   int msaa_sample_count_;
 
   friend class GpuTileTaskWorkerPool;
   DISALLOW_COPY_AND_ASSIGN(GpuRasterizer);
 };
 
 }  // namespace cc
 
 #endif  // CC_RASTER_GPU_RASTERIZER_H_