Fix menu corners: the menu background was being painted as a rect when in fact,

ui/views/controls/menu/menu_host.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 "ui/views/controls/menu/menu_host.h"
 
 #include "ui/gfx/path.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/views/controls/menu/menu_controller.h"
 #include "ui/views/controls/menu/menu_host_root_view.h"
@@ skipping 18 matching lines @@
 }
 
 void MenuHost::InitMenuHost(Widget* parent,
                             const gfx::Rect& bounds,
                             View* contents_view,
                             bool do_capture) {
   Widget::InitParams params(Widget::InitParams::TYPE_MENU);
   params.has_dropshadow = true;
   params.parent = parent ? parent->GetNativeView() : NULL;
   params.bounds = bounds;
+  params.transparent = true;
   Init(params);
 
   if (ui::NativeTheme::IsNewMenuStyleEnabled()) {
     // TODO(yefim): Investigate it more on aura.
     gfx::Path path;
     RoundRectPainter::CreateRoundRectPath(bounds, &path);
     SetShape(path.CreateNativeRegion());
   }
 
   SetContentsView(contents_view);
+  SetOpacity(0);
   ShowMenuHost(do_capture);
 }
 
 bool MenuHost::IsMenuHostVisible() {
   return IsVisible();
 }
 
 void MenuHost::ShowMenuHost(bool do_capture) {
   // Doing a capture may make us get capture lost. Ignore it while we're in the
   // process of showing.
@@ skipping 62 matching lines @@
   if (destroying_)
     return;
 
   MenuController* menu_controller =
       submenu_->GetMenuItem()->GetMenuController();
   if (menu_controller && !menu_controller->drag_in_progress())
     menu_controller->CancelAll();
 }
 
 }  // namespace views