Move HoverButton and HoverImageButton from chrome/browser/ui/cocoa/ to ui/base/cocoa.

chrome/browser/ui/cocoa/hover_image_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.
-
-#import <Cocoa/Cocoa.h>
-
-#include "base/memory/scoped_nsobject.h"
-#include "chrome/browser/ui/cocoa/hover_button.h"
-
-// A button that changes images when you hover over it and click it.
-@interface HoverImageButton : HoverButton {
- @private
-  float defaultOpacity_;
-  float hoverOpacity_;
-  float pressedOpacity_;
-
-  scoped_nsobject<NSImage> defaultImage_;
-  scoped_nsobject<NSImage> hoverImage_;
-  scoped_nsobject<NSImage> pressedImage_;
-}
-
-// Sets the default image.
-- (void)setDefaultImage:(NSImage*)image;
-
-// Sets the hover image.
-- (void)setHoverImage:(NSImage*)image;
-
-// Sets the pressed image.
-- (void)setPressedImage:(NSImage*)image;
-
-// Sets the default opacity.
-- (void)setDefaultOpacity:(float)opacity;
-
-// Sets the opacity on hover.
-- (void)setHoverOpacity:(float)opacity;
-
-// Sets the opacity when pressed.
-- (void)setPressedOpacity:(float)opacity;
-
-@end