compositor-worker: cc->blink mutation plumbing

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index cb9619b1ebaedd6312310b2a156ae1ffb664ed85..42c4e89585e119e1e5a0396cb8e1592fa31a0024 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -568,7 +568,6 @@ bool LayerTreeHost::BeginMainFrameRequested() const {
   return proxy_->BeginMainFrameRequested();
 }
 
-
 void LayerTreeHost::SetNextCommitWaitsForActivation() {
   proxy_->SetNextCommitWaitsForActivation();
 }
@@ -916,6 +915,14 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   }
 }
 
+void LayerTreeHost::ApplyMutations(LayerTreeMutations* mutations) {
+  if (mutations) {
+    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("compositor-worker"),
+                 "LayerTreeHost::ApplyMutations");
+    client_->ApplyMutations(*mutations);
+  }
+}
+
 void LayerTreeHost::SetDeviceScaleFactor(float device_scale_factor) {
   if (device_scale_factor == device_scale_factor_)
     return;