mash: Migrate ScopedTargetRootWindow to //ash/common

ash/aura/scoped_root_window_for_new_windows_aura.h

 // Copyright 2013 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.
 
-#ifndef ASH_SCOPED_TARGET_ROOT_WINDOW_H_
-#define ASH_SCOPED_TARGET_ROOT_WINDOW_H_
+#ifndef ASH_AURA_SCOPED_ROOT_WINDOW_FOR_NEW_WINDOWS_AURA_H_
+#define ASH_AURA_SCOPED_ROOT_WINDOW_FOR_NEW_WINDOWS_AURA_H_
 
 #include "ash/ash_export.h"
+#include "ash/common/scoped_root_window_for_new_windows.h"
 #include "base/macros.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ash {
 
 // Constructing a ScopedTargetRootWindow allows temporarily
 // switching a target root window so that a new window gets created
 // in the same window where a user interaction happened.
 // An example usage is to specify the target root window when creating
 // a new window using launcher's icon.
-class ASH_EXPORT ScopedTargetRootWindow {
+class ASH_EXPORT ScopedRootWindowForNewWindowsAura

[msw, 2016/08/01 21:36:15]

q: Could we cache the WmWindow and make Shell::GetTargetRootWindow convert to an
aura window, instead of creating and vending aura/mus scoped* subclasses?

+    : public ScopedRootWindowForNewWindows {
  public:
-  explicit ScopedTargetRootWindow(aura::Window* root_window);
-  ~ScopedTargetRootWindow();
+  explicit ScopedRootWindowForNewWindowsAura(aura::Window* root_window);
+  ~ScopedRootWindowForNewWindowsAura() override;
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(ScopedTargetRootWindow);
+  DISALLOW_COPY_AND_ASSIGN(ScopedRootWindowForNewWindowsAura);
 };
 
 }  // namespace ash
 
-#endif  // ASH_SCOPED_TARGET_ROOT_WINDOW_H_
+#endif  // ASH_AURA_SCOPED_ROOT_WINDOW_FOR_NEW_WINDOWS_AURA_H_