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

ui/message_center/cocoa/tray_view_controller.mm

 // Copyright (c) 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.
 
 #import "ui/message_center/cocoa/tray_view_controller.h"
 
 #include <cmath>
 
 #include "base/time.h"
 #include "grit/ui_resources.h"
@@ skipping 160 matching lines @@
 
     NSRect pauseButtonFrame = [pauseButton_ frame];
     NSRect clearAllButtonFrame = [clearAllButton_ frame];
     std::swap(clearAllButtonFrame.origin.x, pauseButtonFrame.origin.x);
     [pauseButton_ setFrame:pauseButtonFrame];
     [clearAllButton_ setFrame:clearAllButtonFrame];
   }
 }
 
 - (void)toggleQuietMode:(id)sender {
-  ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   if (messageCenter_->IsQuietMode()) {
     messageCenter_->SetQuietMode(false);
     [pauseButton_ setTrackingEnabled:YES];
-    [pauseButton_ setDefaultImage:
-        rb.GetNativeImageNamed(IDR_NOTIFICATION_PAUSE).ToNSImage()];
   } else {
     messageCenter_->EnterQuietModeWithExpire(base::TimeDelta::FromDays(1));
     [pauseButton_ setTrackingEnabled:NO];
-    [pauseButton_ setDefaultImage:
-        rb.GetNativeImageNamed(IDR_NOTIFICATION_PAUSE_PRESSED).ToNSImage()];
   }
 }
 
 - (void)clearAllNotifications:(id)sender {
   messageCenter_->RemoveAllNotifications(true);
 }
 
 - (void)showSettings:(id)sender {
   // TODO(rsesek): Implement settings.
 }
@@ skipping 106 matching lines @@
   [clearAllButton_ setAction:@selector(clearAllNotifications:)];
   configureButton(clearAllButton_);
   [view addSubview:clearAllButton_];
 
   // Create the pause button.
   defaultImage = rb.GetNativeImageNamed(IDR_NOTIFICATION_PAUSE).ToNSImage();
   NSRect pauseButtonFrame = getButtonFrame(
       NSMinX(clearAllButtonFrame) - kButtonXMargin,
       defaultImage);
   pauseButton_.reset([[HoverImageButton alloc] initWithFrame:pauseButtonFrame]);
+  [pauseButton_ setButtonType:NSToggleButton];
   [pauseButton_ setDefaultImage:defaultImage];
   [pauseButton_ setHoverImage:
       rb.GetNativeImageNamed(IDR_NOTIFICATION_PAUSE_HOVER).ToNSImage()];
   [pauseButton_ setPressedImage:
       rb.GetNativeImageNamed(IDR_NOTIFICATION_PAUSE_PRESSED).ToNSImage()];
   [pauseButton_ setToolTip:
       l10n_util::GetNSString(IDS_MESSAGE_CENTER_QUIET_MODE_BUTTON_TOOLTIP)];
   [pauseButton_ setAction:@selector(toggleQuietMode:)];
   configureButton(pauseButton_);
   [view addSubview:pauseButton_];
 }
 
 @end