Fix WindowTreeHostManager::GetPrimaryRootWindow.

ash/shell.cc

 // Copyright (c) 2012 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 "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 251 matching lines @@
     int64_t display_id) {
   CHECK(HasInstance());
   WmWindow* root_window =
       instance_->shell_port_->GetRootWindowForDisplayId(display_id);
   return root_window ? root_window->GetRootWindowController() : nullptr;
 }
 
 // static
 aura::Window* Shell::GetPrimaryRootWindow() {
   CHECK(HasInstance());
-  return instance_->shell_port_->GetPrimaryRootWindow()->aura_window();
+  WmWindow* wm_window = instance_->shell_port_->GetPrimaryRootWindow();

[varkha, 2017/05/10 22:23:59]

Not for this CL - WmWindow should probably go away here as we are using Aura as
a client lib in mus_ash. Maybe a TODO to make shell_port.h use aura::Window* in
place of WmWindow *.

+  return wm_window ? wm_window->aura_window() : nullptr;
 }
 
 // static
 aura::Window* Shell::GetRootWindowForNewWindows() {
   CHECK(Shell::HasInstance());
   return WmWindow::GetAuraWindow(Shell::GetWmRootWindowForNewWindows());
 }
 
 // static
 WmWindow* Shell::GetWmRootWindowForNewWindows() {
@@ skipping 980 matching lines @@
 void Shell::OnPrefServiceInitialized(
     std::unique_ptr<::PrefService> pref_service) {
   if (!instance_)
     return;
   // |pref_service_| is null if can't connect to Chrome (as happens when
   // running mash outside of chrome --mash and chrome isn't built).
   pref_service_ = std::move(pref_service);
 }
 
 }  // namespace ash