chromeos: Makes mushrome use simplified display management

ui/aura/mus/window_tree_client.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 1470 matching lines @@
   WindowTreeHostMusInitParams init_params;
   init_params.window_port = base::MakeUnique<WindowPortMus>(
       this, WindowMusType::DISPLAY_MANUALLY_CREATED);
   roots_.insert(init_params.window_port.get());
   init_params.window_tree_client = this;
   return init_params;
 }
 
 void WindowTreeClient::OnConnect(ClientSpecificId client_id) {
   client_id_ = client_id;
+  got_initial_displays_ = true;
   if (window_manager_delegate_)
     window_manager_delegate_->OnWmConnected();
 }
 
 void WindowTreeClient::WmNewDisplayAdded(
     const display::Display& display,
     ui::mojom::WindowDataPtr root_data,
     bool parent_drawn,
     const cc::FrameSinkId& frame_sink_id,
     const base::Optional<cc::LocalSurfaceId>& local_surface_id) {
@@ skipping 526 matching lines @@
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForFocus(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightFocusChange>(
       this, focus_synchronizer_.get(), window));
 }
 
 }  // namespace aura