MojoCompositorFrameSinkPrivate should support copy requests

cc/surfaces/compositor_frame_sink_support.cc

 // 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.
 
 #include "cc/surfaces/compositor_frame_sink_support.h"
 
 #include <algorithm>
 #include <utility>
 #include <vector>
 
@@ skipping 229 matching lines @@
   if (needs_begin_frame_ == added_frame_observer_)
     return;
 
   added_frame_observer_ = needs_begin_frame_;
   if (needs_begin_frame_)
     begin_frame_source_->AddObserver(this);
   else
     begin_frame_source_->RemoveObserver(this);
 }
 
+void CompositorFrameSinkSupport::RequestCopyOfSurface(
+    std::unique_ptr<CopyOutputRequest> request) {
+  surface_factory_.RequestCopyOfSurface(std::move(request));
+}
+
 }  // namespace cc