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

ui/views/controls/menu/submenu_view.h

Index: ui/views/controls/menu/submenu_view.h
diff --git a/ui/views/controls/menu/submenu_view.h b/ui/views/controls/menu/submenu_view.h
index f88e266677b026b703c17813e2cb1af7b5345f91..d0bbb18b64c7966dd85826962e34e4f0d2b5448c 100644
--- a/ui/views/controls/menu/submenu_view.h
+++ b/ui/views/controls/menu/submenu_view.h
@@ -100,7 +100,10 @@ class VIEWS_EXPORT SubmenuView : public View,
 
   // Shows the menu at the specified location. Coordinates are in screen
   // coordinates. max_width gives the max width the view should be.
-  void ShowAt(Widget* parent, const gfx::Rect& bounds, bool do_capture);
+  void ShowAt(Widget* parent,
+              const gfx::Rect& bounds,
+              bool do_capture,
+              bool cancel_active_touches);
 
   // Resets the bounds of the submenu to |bounds|.
   void Reposition(const gfx::Rect& bounds);