compositor-worker: Initialize CW machinery plumbing to compositor and fire CW rAF callbacks.

cc/trees/single_thread_proxy.cc

 // Copyright 2011 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/trees/single_thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 346 matching lines @@
     DebugScopedSetImplThread impl(task_runner_provider_);
 
     BlockingTaskRunner::CapturePostTasks blocked(
         task_runner_provider_->blocking_main_thread_task_runner());
     scheduler_on_impl_thread_ = nullptr;
     layer_tree_host_impl_ = nullptr;
   }
   layer_tree_host_ = NULL;
 }
 
+void SingleThreadProxy::SetMutator(std::unique_ptr<LayerTreeMutator> mutator) {
+  DCHECK(task_runner_provider_->IsMainThread());
+  DebugScopedSetImplThread impl(task_runner_provider_);
+  layer_tree_host_impl_->SetLayerTreeMutator(std::move(mutator));
+}
+
 void SingleThreadProxy::OnCanDrawStateChanged(bool can_draw) {
   TRACE_EVENT1(
       "cc", "SingleThreadProxy::OnCanDrawStateChanged", "can_draw", can_draw);
   DCHECK(task_runner_provider_->IsImplThread());
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetCanDraw(can_draw);
 }
 
 void SingleThreadProxy::NotifyReadyToActivate() {
   TRACE_EVENT0("cc", "SingleThreadProxy::NotifyReadyToActivate");
@@ skipping 535 matching lines @@
       << "DidFinishImplFrame called while not inside an impl frame!";
   inside_impl_frame_ = false;
 #endif
 }
 
 void SingleThreadProxy::SendBeginFramesToChildren(const BeginFrameArgs& args) {
   layer_tree_host_->SendBeginFramesToChildren(args);
 }
 
 }  // namespace cc