WIP - compositor worker mega patch.

cc/trees/proxy_main.cc

Index: cc/trees/proxy_main.cc
diff --git a/cc/trees/proxy_main.cc b/cc/trees/proxy_main.cc
index 2175e7fb182020dbe9fee68a7cfb5d27fbcd4630..5c81cefba0a9e2261fa631c38a085f517a2e81b6 100644
--- a/cc/trees/proxy_main.cc
+++ b/cc/trees/proxy_main.cc
@@ -175,6 +175,9 @@ void ProxyMain::BeginMainFrame(
   layer_tree_host_->ApplyScrollAndScale(
       begin_main_frame_state->scroll_info.get());
 
+  layer_tree_host_->ApplyMutations(
+      begin_main_frame_state->mutations.get());
+
   layer_tree_host_->WillBeginMainFrame();
 
   layer_tree_host_->BeginMainFrame(begin_main_frame_state->begin_frame_args);
@@ -401,6 +404,11 @@ void ProxyMain::Stop() {
   started_ = false;
 }
 
+void ProxyMain::SetMutator(LayerTreeMutator* mutator) {
+  TRACE_EVENT0("compositor-worker", "ThreadProxy::SetMutator");
+  channel_main_->InitializeMutatorOnImpl(mutator);
+}
+
 bool ProxyMain::SupportsImplScrolling() const {
   return true;
 }