mac: Disable CoreAnimation throbbers for now, while I investigate the performance regressions.

chrome/browser/ui/cocoa/tabs/throbber_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_THROBBER_VIEW_H_
 #define CHROME_BROWSER_UI_COCOA_TABS_THROBBER_VIEW_H_
 
 #import <Cocoa/Cocoa.h>
 
 @protocol ThrobberDataDelegate;
 
 // Draws an image animating down to the bottom and then another image
 // animating up from the bottom. Stops once the animation is complete.
 
 @interface ThrobberView : NSView {
  @private
   id<ThrobberDataDelegate> dataDelegate_;
 }
 
+// Creates a filmstrip view with |frame| and image |image|.
++ (id)filmstripThrobberViewWithFrame:(NSRect)frame
+                               image:(NSImage*)image;
+
 // Creates a toast view with |frame| and specified images.
 + (id)toastThrobberViewWithFrame:(NSRect)frame
                      beforeImage:(NSImage*)beforeImage
                       afterImage:(NSImage*)afterImage;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_TABS_THROBBER_VIEW_H_