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

cc/trees/proxy_impl.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_impl.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 105 matching lines @@
   external_begin_frame_source_ = nullptr;
   unthrottled_begin_frame_source_ = nullptr;
   synthetic_begin_frame_source_ = nullptr;
   layer_tree_host_impl_ = nullptr;
   // We need to explicitly shutdown the notifier to destroy any weakptrs it is
   // holding while still on the compositor thread. This also ensures any
   // callbacks holding a ProxyImpl pointer are cancelled.
   smoothness_priority_expiration_notifier_.Shutdown();
 }
 
+void ProxyImpl::InitializeMutatorOnImpl(
+    std::unique_ptr<LayerTreeMutator> mutator) {
+  TRACE_EVENT0("cc,compositor-worker", "ProxyImpl::InitializeMutatorOnImpl");
+  DCHECK(IsImplThread());
+  layer_tree_host_impl_->SetLayerTreeMutator(std::move(mutator));
+}
+
 void ProxyImpl::UpdateTopControlsStateOnImpl(TopControlsState constraints,
                                              TopControlsState current,
                                              bool animate) {
   DCHECK(IsImplThread());
   layer_tree_host_impl_->top_controls_manager()->UpdateTopControlsState(
       constraints, current, animate);
 }
 
 void ProxyImpl::InitializeOutputSurfaceOnImpl(OutputSurface* output_surface) {
   TRACE_EVENT0("cc", "ProxyImpl::InitializeOutputSurfaceOnImplThread");
@@ skipping 554 matching lines @@
 bool ProxyImpl::IsMainThreadBlocked() const {
   return task_runner_provider_->IsMainThreadBlocked();
 }
 
 ProxyImpl::BlockedMainCommitOnly& ProxyImpl::blocked_main_commit() {
   DCHECK(IsMainThreadBlocked() && commit_completion_event_);
   return main_thread_blocked_commit_vars_unsafe_;
 }
 
 }  // namespace cc