Create a cross-platform browsertest for the browser actions bar

chrome/browser/ui/cocoa/extensions/browser_actions_controller.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/extensions/browser_actions_controller.h"
 
 #include <cmath>
 #include <string>
 
 #include "base/strings/sys_string_conversions.h"
@@ skipping 834 matching lines @@
       browser_->tab_strip_model()->GetActiveWebContents();
   if (!active_tab)
     return -1;
 
   return SessionTabHelper::FromWebContents(active_tab)->session_id().id();
 }
 
 #pragma mark -
 #pragma mark Testing Methods
 
-- (NSButton*)buttonWithIndex:(NSUInteger)index {
+- (BrowserActionButton*)buttonWithIndex:(NSUInteger)index {
   const extensions::ExtensionList& toolbar_items =
       toolbarModel_->toolbar_items();
   if (index < toolbar_items.size()) {
     const Extension* extension = toolbar_items[index].get();
     return [buttons_ objectForKey:base::SysUTF8ToNSString(extension->id())];
   }
   return nil;
 }
 
 @end