Update from https://crrev.com/312600

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index 243e6033ea0ddc8959cad5bdb67b2d40135e8cf6..4b360a4e806406ff03c0ea3f48389e853bebb725 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -267,6 +267,11 @@ void ThreadProxy::SendCommitRequestToImplThreadIfNeeded() {
                  impl_thread_weak_ptr_));
 }
 
+void ThreadProxy::DidCompletePageScaleAnimation() {
+  DCHECK(IsMainThread());
+  layer_tree_host()->DidCompletePageScaleAnimation();
+}
+
 const RendererCapabilities& ThreadProxy::GetRendererCapabilities() const {
   DCHECK(IsMainThread());
   DCHECK(!layer_tree_host()->output_surface_lost());
@@ -1353,4 +1358,11 @@ void ThreadProxy::DidPrepareTiles() {
   impl().scheduler->DidPrepareTiles();
 }
 
+void ThreadProxy::DidCompletePageScaleAnimationOnImplThread() {
+  DCHECK(IsImplThread());
+  Proxy::MainThreadTaskRunner()->PostTask(
+      FROM_HERE, base::Bind(&ThreadProxy::DidCompletePageScaleAnimation,
+                            main_thread_weak_ptr_));
+}
+
 }  // namespace cc