[Mac][Material Design] Fix ghosting of cast and other extension icons.

chrome/browser/ui/cocoa/toolbar/toolbar_button_cocoa.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 CHROME_BROWSER_UI_COCOA_TOOLBAR_TOOLBAR_BUTTON_COCOA_H_
 #define CHROME_BROWSER_UI_COCOA_TOOLBAR_TOOLBAR_BUTTON_COCOA_H_
 
 #import <Cocoa/Cocoa.h>
 
+#import "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #import "ui/gfx/color_utils.h"
 #include "ui/gfx/vector_icons_public.h"
 
 enum class ToolbarButtonImageBackgroundStyle {
+  DEFAULT,
   HOVER,
   HOVER_THEMED,
   PRESSED,
   PRESSED_THEMED,
 };
 
 // NSButton subclass which handles middle mouse clicking.
 @interface ToolbarButton : NSButton<ThemedWindowDrawing>  {
  @protected
+  // The toolbar button's image, as assigned by setImage:.
+  base::scoped_nsobject<NSImage> image_;
+
   // YES when middle mouse clicks should be handled.
   BOOL handleMiddleClick_;
 }
 
 // Return the size of toolbar buttons.
 + (NSSize)toolbarButtonSize;
 // Whether or not to handle the mouse middle click events.
 @property(assign, nonatomic) BOOL handleMiddleClick;
 // Override point for subclasses to return their vector icon id.
 - (gfx::VectorIconId)vectorIconId;
 // Override point for subclasses to return their vector icon color.
 - (SkColor)vectorIconColor:(BOOL)themeIsDark;
 // When in Material Design mode, sets the images for each of the ToolbarButton's
 // states from the specified image.
 - (void)setImage:(NSImage*)anImage;
 // Resets the images for each of the ToolbarButton's states from its vector icon
 // id or its main image. Should only be called when in Material Design mode.
 - (void)resetButtonStateImages;
 @end
 
 @interface ToolbarButton (ExposedForTesting)
 - (BOOL)shouldHandleEvent:(NSEvent*)theEvent;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_TOOLBAR_TOOLBAR_BUTTON_COCOA_H_