Rename RootWindowHost to WindowTreeHost

ui/aura/root_window_observer.h

 // 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.
 
 #ifndef UI_AURA_ROOT_WINDOW_OBSERVER_H_
 #define UI_AURA_ROOT_WINDOW_OBSERVER_H_
 
 #include "ui/aura/aura_export.h"
 
 namespace gfx {
 class Point;
 class Size;
 }
 
 namespace aura {
 class RootWindow;
 class Window;
 
 class AURA_EXPORT RootWindowObserver {
  public:
   // Invoked after the RootWindow's host has been resized.
-  virtual void OnRootWindowHostResized(const RootWindow* root) {}
+  virtual void OnWindowTreeHostResized(const RootWindow* root) {}
 
   // Invoked after the RootWindow's host has been moved on screen.
-  virtual void OnRootWindowHostMoved(const RootWindow* root,
+  virtual void OnWindowTreeHostMoved(const RootWindow* root,
                                      const gfx::Point& new_origin) {}
 
   // Invoked when the native windowing system sends us a request to close our
   // window.
-  virtual void OnRootWindowHostCloseRequested(const RootWindow* root) {}
+  virtual void OnWindowTreeHostCloseRequested(const RootWindow* root) {}
 
   // Invoked when the keyboard mapping has changed.
   virtual void OnKeyboardMappingChanged(const RootWindow* root) {}
 
  protected:
   virtual ~RootWindowObserver() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_OBSERVER_H_