Relocate and refactor overview mode files.

ash/wm/overview/window_selector_delegate.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_WM_WINDOW_SELECTOR_DELEGATE_H_
-#define ASH_WM_WINDOW_SELECTOR_DELEGATE_H_
+#ifndef ASH_WM_OVERVIEW_WINDOW_SELECTOR_DELEGATE_H_
+#define ASH_WM_OVERVIEW_WINDOW_SELECTOR_DELEGATE_H_
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ash {
 
 // Implement this class to handle the selection event from WindowSelector.
 class ASH_EXPORT WindowSelectorDelegate {
  public:
   // Invoked when a window is selected.
   virtual void OnWindowSelected(aura::Window* window) = 0;
 
   // Invoked if selection is canceled.
   virtual void OnSelectionCanceled() = 0;
 
  protected:
   virtual ~WindowSelectorDelegate() {}
 };
 
 }  // namespace ash
 
-#endif  // ASH_WM_WINDOW_SELECTOR_DELEGATE_H_
+#endif  // ASH_WM_OVERVIEW_WINDOW_SELECTOR_DELEGATE_H_