compositor-worker: blink->cc plumbing

cc/trees/threaded_channel.cc

Index: cc/trees/threaded_channel.cc
diff --git a/cc/trees/threaded_channel.cc b/cc/trees/threaded_channel.cc
index 07b17cb571cc5c4798e28737a34323462064f8a2..aa0290ed16c60f942df826638af5e8e85001838b 100644
--- a/cc/trees/threaded_channel.cc
+++ b/cc/trees/threaded_channel.cc
@@ -8,6 +8,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/animation/animation_events.h"
+#include "cc/animation/layer_tree_mutator.h"
 #include "cc/trees/layer_tree_host.h"
 
 namespace cc {
@@ -53,6 +54,12 @@ void ThreadedChannel::InitializeOutputSurfaceOnImpl(
                             proxy_impl_weak_ptr_, output_surface));
 }
 
+void ThreadedChannel::InitializeMutatorOnImpl(LayerTreeMutator* mutator) {
+  ImplThreadTaskRunner()->PostTask(
+      FROM_HERE, base::Bind(&ProxyImpl::InitializeMutatorOnImpl,
+                            proxy_impl_weak_ptr_, mutator));
+}
+
 void ThreadedChannel::MainThreadHasStoppedFlingingOnImpl() {
   DCHECK(IsMainThread());
   ImplThreadTaskRunner()->PostTask(