[Mac] Update tab audio icon to Material Design and tweak close box color.

chrome/browser/ui/cocoa/tabs/tab_view.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_TABS_TAB_VIEW_H_
 #define CHROME_BROWSER_UI_COCOA_TABS_TAB_VIEW_H_
 
 #include <ApplicationServices/ApplicationServices.h>
 #import <Cocoa/Cocoa.h>
 
@@ skipping 103 matching lines @@
 - (void)startAlert;
 
 // Stop showing the "alert" glow; this won't immediately wipe out any glow, but
 // will make it fade away.
 - (void)cancelAlert;
 
 // Returns the width of the largest part of the tab that is available for the
 // user to click to select/activate the tab.
 - (int)widthOfLargestSelectableRegion;
 
+// Returns the Material Design color of the "x".
+- (SkColor)closeButtonColor;
+
 @end
 
 // The TabController |controller_| is not the only owner of this view. If the
 // controller is released before this view, then we could be hanging onto a
 // garbage pointer. To prevent this, the TabController uses this interface to
 // clear the |controller_| pointer when it is dying.
 @interface TabView (TabControllerInterface)
 - (void)setController:(TabController*)controller;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_TABS_TAB_VIEW_H_