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

chrome/browser/ui/cocoa/hover_image_button.mm

-// 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 "chrome/browser/ui/cocoa/hover_image_button.h"
-
-#include "base/memory/scoped_nsobject.h"
-#include "grit/generated_resources.h"
-#include "ui/base/l10n/l10n_util.h"
-
-@implementation HoverImageButton
-
-- (void)drawRect:(NSRect)rect {
-  if (hoverState_ == kHoverStateMouseDown && pressedImage_) {
-    [super setImage:pressedImage_.get()];
-    [super setAlphaValue:pressedOpacity_];
-  } else if (hoverState_ == kHoverStateMouseOver && hoverImage_) {
-    [super setImage:hoverImage_.get()];
-    [super setAlphaValue:hoverOpacity_];
-  } else {
-    [super setImage:defaultImage_.get()];
-    [super setAlphaValue:defaultOpacity_];
-  }
-
-  [super drawRect:rect];
-}
-
-- (void)setDefaultImage:(NSImage*)image {
-  defaultImage_.reset([image retain]);
-}
-
-- (void)setDefaultOpacity:(float)opacity {
-  defaultOpacity_ = opacity;
-}
-
-- (void)setHoverImage:(NSImage*)image {
-  hoverImage_.reset([image retain]);
-}
-
-- (void)setHoverOpacity:(float)opacity {
-  hoverOpacity_ = opacity;
-}
-
-- (void)setPressedImage:(NSImage*)image {
-  pressedImage_.reset([image retain]);
-}
-
-- (void)setPressedOpacity:(float)opacity {
-  pressedOpacity_ = opacity;
-}
-
-@end