[UI Views] Don't allow a ButtonListener and a MenuButtonListener

chrome/browser/ui/views/tab_icon_view.cc

 // 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.
 
 #include "chrome/browser/ui/views/tab_icon_view.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif
@@ skipping 39 matching lines @@
     DestroyIcon(app_icon);
 #else
     ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
     g_default_favicon = rb.GetImageSkiaNamed(IDR_PRODUCT_LOGO_16);
 #endif
   }
 }
 
 TabIconView::TabIconView(TabIconViewModel* model,
                          views::MenuButtonListener* listener)
-    : views::MenuButton(NULL, base::string16(), listener, false),
+    : views::MenuButton(base::string16(), listener, false),
       model_(model),
       is_light_(false) {
   InitializeIfNeeded();
 }
 
 TabIconView::~TabIconView() {
 }
 
 void TabIconView::Update() {
   if (!model_->ShouldTabIconViewAnimate())
@@ skipping 60 matching lines @@
     gfx::ImageSkia favicon = model_->GetFaviconForTabIconView();
     if (!favicon.isNull()) {
       rendered = true;
       PaintFavicon(canvas, favicon);
     }
   }
 
   if (!rendered)
     PaintFavicon(canvas, *g_default_favicon);
 }