Add Mojo API for Blink hit testing

ui/aura/local/layer_tree_frame_sink_local.cc

 // Copyright 2017 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 "ui/aura/local/layer_tree_frame_sink_local.h"
 
 #include "cc/output/layer_tree_frame_sink_client.h"
 #include "components/viz/host/host_frame_sink_manager.h"
 #include "components/viz/service/frame_sinks/compositor_frame_sink_support.h"
 #include "ui/aura/client/cursor_client.h"
@@ skipping 15 matching lines @@
 LayerTreeFrameSinkLocal::~LayerTreeFrameSinkLocal() {}
 
 bool LayerTreeFrameSinkLocal::BindToClient(
     cc::LayerTreeFrameSinkClient* client) {
   if (!cc::LayerTreeFrameSink::BindToClient(client))
     return false;
   DCHECK(!thread_checker_);
   thread_checker_ = base::MakeUnique<base::ThreadChecker>();
 
   support_ = host_frame_sink_manager_->CreateCompositorFrameSinkSupport(
-      this, frame_sink_id_, false /* is_root */,
+      this, nullptr, frame_sink_id_, false /* is_root */,
       true /* handles_frame_sink_id_invalidation */,
       true /* needs_sync_points */);
   begin_frame_source_ = base::MakeUnique<viz::ExternalBeginFrameSource>(this);
   client->SetBeginFrameSource(begin_frame_source_.get());
   return true;
 }
 
 void LayerTreeFrameSinkLocal::SetSurfaceChangedCallback(
     const SurfaceChangedCallback& callback) {
   DCHECK(!surface_changed_callback_);
@@ skipping 78 matching lines @@
   client_->ReclaimResources(resources);
 }
 
 void LayerTreeFrameSinkLocal::OnNeedsBeginFrames(bool needs_begin_frames) {
   DCHECK(thread_checker_);
   DCHECK(thread_checker_->CalledOnValidThread());
   support_->SetNeedsBeginFrame(needs_begin_frames);
 }
 
 }  // namespace aura