mac: Remove unused includes of scoped_nsobject.h.

ui/base/cocoa/hover_button.h

 // Copyright (c) 2011 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_BASE_COCOA_HOVER_BUTTON_
 #define UI_BASE_COCOA_HOVER_BUTTON_
 
 #import <Cocoa/Cocoa.h>
 
-#import "base/mac/scoped_nsobject.h"
 #import "ui/base/cocoa/tracking_area.h"
 #import "ui/base/ui_export.h"
 
 // A button that changes when you hover over it and click it.
 UI_EXPORT
 @interface HoverButton : NSButton {
  @protected
   // Enumeration of the hover states that the close button can be in at any one
   // time. The button cannot be in more than one hover state at a time.
   enum HoverState {
@@ skipping 16 matching lines @@
 
 // Checks to see whether the mouse is in the button's bounds and update
 // the image in case it gets out of sync.  This occurs to the close button
 // when you close a tab so the tab to the left of it takes its place, and
 // drag the button without moving the mouse before you press the button down.
 - (void)checkImageState;
 
 @end
 
 #endif  // UI_BASE_COCOA_HOVER_BUTTON_