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

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 9c31c68db9daa3b2603a13a5b74bd053d6acfd2e..585bd0bb6ff4ce25d56ea8606fad01bf71828aab 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -1214,6 +1214,7 @@ ResourceProvider::ResourceProvider(
       yuv_resource_format_(LUMINANCE_8),
       max_texture_size_(0),
       best_texture_format_(RGBA_8888),
+      best_render_buffer_format_(RGBA_8888),
       use_rgba_4444_texture_format_(use_rgba_4444_texture_format),
       id_allocation_chunk_size_(id_allocation_chunk_size),
       use_sync_query_(false),
@@ -1256,6 +1257,9 @@ void ResourceProvider::Initialize() {
   best_texture_format_ =
       PlatformColor::BestTextureFormat(use_texture_format_bgra_);
 
+  best_render_buffer_format_ =
+      PlatformColor::BestTextureFormat(caps.gpu.render_buffer_format_bgra8888);
+
   texture_id_allocator_.reset(
       new TextureIdAllocator(gl, id_allocation_chunk_size_));
   buffer_id_allocator_.reset(