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

cc/trees/proxy_main.cc

 // Copyright 2015 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/proxy_main.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/trace_event/trace_event.h"
@@ skipping 386 matching lines @@
   TRACE_EVENT0("cc", "ProxyMain::Stop");
   DCHECK(IsMainThread());
   DCHECK(started_);
 
   channel_main_->SynchronouslyCloseImpl();
 
   layer_tree_host_ = nullptr;
   started_ = false;
 }
 
+void ProxyMain::SetMutator(std::unique_ptr<LayerTreeMutator> mutator) {
+  TRACE_EVENT0("compositor-worker", "ThreadProxy::SetMutator");
+  channel_main_->InitializeMutatorOnImpl(std::move(mutator));
+}
+
 bool ProxyMain::SupportsImplScrolling() const {
   return true;
 }
 
 bool ProxyMain::MainFrameWillHappenForTesting() {
   DCHECK(IsMainThread());
   bool main_frame_will_happen = false;
   {
     DebugScopedSetMainThreadBlocked main_thread_blocked(task_runner_provider_);
     CompletionEvent completion;
@@ skipping 40 matching lines @@
     return false;
   channel_main_->SetNeedsCommitOnImpl();
   return true;
 }
 
 bool ProxyMain::IsMainThread() const {
   return task_runner_provider_->IsMainThread();
 }
 
 }  // namespace cc