Change primordial pipes to ShellClient

components/mus/ws/display.cc

 // Copyright 2015 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 "components/mus/ws/display.h"
 
 #include "base/debug/debugger.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/mus/common/types.h"
 #include "components/mus/ws/connection_manager.h"
@@ skipping 308 matching lines @@
     for (auto& pair : window_manager_state_map_)
       pair.second->root()->SetBounds(wm_bounds);
   }
   // TODO(sky): if bounds changed, then need to update
   // Display/WindowManagerState appropriately (e.g. notify observers).
   connection_manager_->ProcessViewportMetricsChanged(this, old_metrics,
                                                      new_metrics);
 }
 
 void Display::OnTopLevelSurfaceChanged(cc::SurfaceId surface_id) {
-  DCHECK(!root_);
-  // This should only be called once, and before we've created root_.
+  // This should only be called twice: once before we've created root_, and once
+  // during shutdown, when |surface_id| will be null.
+  DCHECK(!root_ || surface_id.is_null());
   top_level_surface_id_ = surface_id;
 }
 
 void Display::OnCompositorFrameDrawn() {
   std::set<ServerWindow*> windows;
   windows.swap(windows_needing_frame_destruction_);
   for (ServerWindow* window : windows) {
     window->RemoveObserver(this);
     window->DestroySurfacesScheduledForDestruction();
   }
@@ skipping 137 matching lines @@
   DCHECK_EQ(0u, window_manager_state_map_.count(id));
 }
 
 void Display::OnWindowManagerFactorySet(WindowManagerFactoryService* service) {
   if (!binding_)
     CreateWindowManagerStateFromService(service);
 }
 
 }  // namespace ws
 }  // namespace mus