mash: Port KeyboardUIMus to mojo:ash; remove sysui.

ash/root_window_controller.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/root_window_controller.h"
 
 #include <queue>
 #include <vector>
 
 #include "ash/aura/aura_layout_manager_adapter.h"
@@ skipping 818 matching lines @@
 }
 
 void RootWindowController::OnTouchHudProjectionToggled(bool enabled) {
   if (enabled)
     EnableTouchHudProjection();
   else
     DisableTouchHudProjection();
 }
 
 RootWindowController* GetRootWindowController(const aura::Window* root_window) {
-  if (!root_window)
-    return nullptr;
-
-  if (Shell::GetInstance()->in_mus()) {
-    // On mus, like desktop aura, each top-level widget has its own root window,
-    // so |root_window| is not necessarily the display's root. For now, just
-    // the use the primary display root.
-    // TODO(jamescook): Multi-display support. This depends on how mus windows
-    // will be owned by displays.
-    aura::Window* primary_root_window = Shell::GetInstance()
-                                            ->window_tree_host_manager()
-                                            ->GetPrimaryRootWindow();
-    return GetRootWindowSettings(primary_root_window)->controller;
-  }
-
-  return GetRootWindowSettings(root_window)->controller;
+  return root_window ? GetRootWindowSettings(root_window)->controller : nullptr;
 }
 
 }  // namespace ash