Gets chrome --mus some what working

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index da326eaacc31fbbd72b5c6e81e84700cfdfc116c..db0ab724dc6e9db8d60356aa76c3fb7983ae77a2 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -553,6 +553,8 @@ WindowTreeHostMus* WindowTreeClient::WmNewDisplayAddedImpl(
     const cc::FrameSinkId& frame_sink_id) {
   DCHECK(window_manager_delegate_);
 
+  got_initial_displays_ = true;
+
   window_manager_delegate_->OnWmWillCreateDisplay(display);
 
   std::unique_ptr<WindowTreeHostMus> window_tree_host = CreateWindowTreeHost(
@@ -1366,6 +1368,17 @@ void WindowTreeClient::RequestClose(uint32_t window_id) {
   GetWindowTreeHostMus(window->GetWindow())->OnCloseRequest();
 }
 
+bool WindowTreeClient::WaitForInitialDisplays() {
+  if (got_initial_displays_)
+    return true;
+
+  bool valid_wait = true;
+  // TODO(sky): having to block here is not ideal. http://crbug.com/594852.
+  while (!got_initial_displays_ && valid_wait)
+    valid_wait = binding_.WaitForIncomingMethodCall();
+  return valid_wait;
+}
+
 void WindowTreeClient::OnConnect(ClientSpecificId client_id) {
   client_id_ = client_id;
 }