Adds MUSViewsInit

components/mus/public/cpp/lib/view_tree_client_impl.cc

Index: components/mus/public/cpp/lib/view_tree_client_impl.cc
diff --git a/components/mus/public/cpp/lib/view_tree_client_impl.cc b/components/mus/public/cpp/lib/view_tree_client_impl.cc
index 2a8516c29d6e0571ed860c0a1d2ba26459400717..bd2a8ebbd3572814370db9641ffe151a29db29c6 100644
--- a/components/mus/public/cpp/lib/view_tree_client_impl.cc
+++ b/components/mus/public/cpp/lib/view_tree_client_impl.cc
@@ -70,8 +70,12 @@ View* BuildViewTree(ViewTreeClientImpl* client,
 
 ViewTreeConnection* ViewTreeConnection::Create(
     ViewTreeDelegate* delegate,
-    mojo::InterfaceRequest<mojo::ViewTreeClient> request) {
-  return new ViewTreeClientImpl(delegate, request.Pass());
+    mojo::InterfaceRequest<mojo::ViewTreeClient> request,
+    CreateType create_type) {
+  ViewTreeClientImpl* client = new ViewTreeClientImpl(delegate, request.Pass());
+  if (create_type == CreateType::WAIT_FOR_EMBED)
+    client->WaitForEmbed();
+  return client;
 }
 
 ViewTreeClientImpl::ViewTreeClientImpl(
@@ -112,6 +116,13 @@ ViewTreeClientImpl::~ViewTreeClientImpl() {
   delegate_->OnConnectionLost(this);
 }
 
+void ViewTreeClientImpl::WaitForEmbed() {
+  DCHECK(!root_);
+  // OnEmbed() is the first function called.
+  binding_.WaitForIncomingMethodCall();
+  // TODO(sky): deal with pipe being closed before we get OnEmbed().
+}
+
 void ViewTreeClientImpl::DestroyView(Id view_id) {
   DCHECK(tree_);
   tree_->DeleteView(view_id, ActionCompletedCallback());