[Mac] Reimplement HoverButton and HoverImageButton using NSButton.state.

ui/base/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 "ui/base/cocoa/hover_image_button.h"
 
 @implementation HoverImageButton
 
-- (void)drawRect:(NSRect)rect {
-  if (hoverState_ == kHoverStateMouseDown && pressedImage_) {
-    [super setImage:pressedImage_.get()];
-  } else if (hoverState_ == kHoverStateMouseOver && hoverImage_) {
-    [super setImage:hoverImage_.get()];
-  } else {
-    [super setImage:defaultImage_.get()];
-  }
+- (void)setIsMouseInside:(BOOL)isInside {
+  if (isInside && hoverImage_)
+    [self setImage:hoverImage_];
+  else
+    [self setImage:defaultImage_];
 
-  [super drawRect:rect];
+  [super setIsMouseInside:isInside];
 }
 
 - (void)setDefaultImage:(NSImage*)image {
   defaultImage_.reset([image retain]);
+  [self checkImageState];
 }
 
 - (void)setHoverImage:(NSImage*)image {
   hoverImage_.reset([image retain]);
+  [self checkImageState];
 }
 
 - (void)setPressedImage:(NSImage*)image {
-  pressedImage_.reset([image retain]);
+  [self setAlternateImage:image];
 }
 
 @end