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

cc/resources/resource_provider.h

Index: cc/resources/resource_provider.h
diff --git a/cc/resources/resource_provider.h b/cc/resources/resource_provider.h
index 2130bb7b1a983b19cfc9342aedcc5b75a66617f7..7038a7938cc5b5d3fbf38403531f054854ba82d4 100644
--- a/cc/resources/resource_provider.h
+++ b/cc/resources/resource_provider.h
@@ -96,6 +96,9 @@ class CC_EXPORT ResourceProvider {
     return use_rgba_4444_texture_format_ ? RGBA_4444 : best_texture_format_;
   }
   ResourceFormat best_texture_format() const { return best_texture_format_; }
+  ResourceFormat best_render_buffer_format() const {
+    return best_render_buffer_format_;
+  }
   ResourceFormat yuv_resource_format() const { return yuv_resource_format_; }
   bool use_sync_query() const { return use_sync_query_; }
   bool use_persistent_map_for_gpu_memory_buffers() const {
@@ -596,6 +599,7 @@ class CC_EXPORT ResourceProvider {
   scoped_ptr<TextureUploader> texture_uploader_;
   int max_texture_size_;
   ResourceFormat best_texture_format_;
+  ResourceFormat best_render_buffer_format_;
 
   base::ThreadChecker thread_checker_;