Make shelf item can be dragged when context menu is opened.

ui/views/controls/menu/menu_host.h

 // 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.
 
 #ifndef UI_VIEWS_CONTROLS_MENU_MENU_HOST_H_
 #define UI_VIEWS_CONTROLS_MENU_MENU_HOST_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 49 matching lines @@
 
   // Destroys and deletes the menu host.
   void DestroyMenuHost();
 
   // Sets the bounds of the menu host.
   void SetMenuHostBounds(const gfx::Rect& bounds);
 
   // Releases a mouse grab installed by |ShowMenuHost|.
   void ReleaseMenuHostCapture();
 
+  void TransferEvents(Widget* source, Widget* target);

[xiyuan, 2017/05/15 19:20:52]

This does not depend on any MenuHost state and not called externally. So let's
put it in an anonymous namespace in cc file. Also maybe call it TransferGesture
to be more accurate.

[minch1, 2017/05/16 22:13:39]

Done.

+
  private:
   friend class test::MenuControllerTest;
 
   // Overridden from Widget:
   internal::RootView* CreateRootView() override;
   void OnMouseCaptureLost() override;
   void OnNativeWidgetDestroyed() override;
   void OnOwnerClosing() override;
   void OnDragWillStart() override;
   void OnDragComplete() override;
 
   // The view we contain.
   SubmenuView* submenu_;
 
+  Widget* owner_ = NULL;

[xiyuan, 2017/05/15 19:20:52]

Document the member and insert an empty line after it.

[xiyuan, 2017/05/15 19:20:52]

NULL -> nullptr

[minch1, 2017/05/16 22:13:39]

Done.

   // If true, DestroyMenuHost has been invoked.
   bool destroying_;
 
   // If true and capture is lost we don't notify the delegate.
   bool ignore_capture_lost_;
 
 #if !defined(OS_MACOSX)
   // Handles raw touch events at the moment.
   std::unique_ptr<internal::PreMenuEventDispatchHandler> pre_dispatch_handler_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(MenuHost);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_MENU_MENU_HOST_H_