[WIP] cc: Plumb SurfaceId from clients

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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 "content/renderer/gpu/render_widget_compositor.h"
 
 #include <stddef.h>
 #include <limits>
 #include <string>
 #include <utility>
@@ skipping 1107 matching lines @@
 
 void RenderWidgetCompositor::SendCompositorProto(
     const cc::proto::CompositorMessage& proto) {
   int signed_size = proto.ByteSize();
   size_t unsigned_size = base::checked_cast<size_t>(signed_size);
   std::vector<uint8_t> serialized(unsigned_size);
   proto.SerializeToArray(serialized.data(), signed_size);
   delegate_->ForwardCompositorProto(serialized);
 }
 
+uint32_t RenderWidgetCompositor::GetSurfaceClientId() const {
+  return layer_tree_host_->surface_client_id();
+}
+
 void RenderWidgetCompositor::SetSurfaceClientId(uint32_t surface_client_id) {
   layer_tree_host_->set_surface_client_id(surface_client_id);
 }
 
 void RenderWidgetCompositor::OnHandleCompositorProto(
     const std::vector<uint8_t>& proto) {
   DCHECK(remote_proto_channel_receiver_);
 
   std::unique_ptr<cc::proto::CompositorMessage> deserialized(
       new cc::proto::CompositorMessage);
   int signed_size = base::checked_cast<int>(proto.size());
   if (!deserialized->ParseFromArray(proto.data(), signed_size)) {
     LOG(ERROR) << "Unable to parse compositor proto.";
     return;
   }
 
   remote_proto_channel_receiver_->OnProtoReceived(std::move(deserialized));
 }
 
 void RenderWidgetCompositor::SetPaintedDeviceScaleFactor(
     float device_scale) {
   layer_tree_host_->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 }  // namespace content