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

chrome/browser/ui/views/profiles/avatar_menu_button.cc

 // Copyright 2014 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/profiles/avatar_menu_button.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "build/build_config.h"
@@ skipping 19 matching lines @@
 #include "ui/views/widget/widget.h"
 
 static inline int Round(double x) {
   return static_cast<int>(x + 0.5);
 }
 
 // static
 const char AvatarMenuButton::kViewClassName[] = "AvatarMenuButton";
 
 AvatarMenuButton::AvatarMenuButton(BrowserView* browser_view)
-    : MenuButton(NULL, base::string16(), this, false),
+    : MenuButton(base::string16(), this, false),
       browser_view_(browser_view),
       enabled_(browser_view_->IsRegularOrGuestSession()),
       is_rectangle_(false),
       old_height_(0) {
   // In RTL mode, the avatar icon should be looking the opposite direction.
   EnableCanvasFlippingForRTLUI(true);
 
   SetEventTargeter(
       scoped_ptr<views::ViewTargeter>(new views::ViewTargeter(this)));
 }
@@ skipping 97 matching lines @@
   return enabled_ &&
          views::ViewTargeterDelegate::DoesIntersectRect(target, rect);
 }
 
 // views::MenuButtonListener implementation
 void AvatarMenuButton::OnMenuButtonClicked(views::View* source,
                                            const gfx::Point& point) {
   if (enabled_)
     chrome::ShowAvatarMenu(browser_view_->browser());
 }