Allow menus to stay open during a child view's drag and drop

ui/views/widget/widget.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_WIDGET_WIDGET_H_
 #define UI_VIEWS_WIDGET_WIDGET_H_
 
 #include <set>
 #include <stack>
 #include <vector>
@@ skipping 775 matching lines @@
   // Creates the RootView to be used within this Widget. Subclasses may override
   // to create custom RootViews that do specialized event processing.
   // TODO(beng): Investigate whether or not this is needed.
   virtual internal::RootView* CreateRootView();
 
   // Provided to allow the NativeWidget implementations to destroy the RootView
   // _before_ the focus manager/tooltip manager.
   // TODO(beng): remove once we fold those objects onto this one.
   void DestroyRootView();
 
+  // Notification that a drag will start. Default implementation does nothing.
+  virtual void OnDragWillStart();
+
+  // Notification that the drag performed by RunShellDrag() has completed.
+  virtual void OnDragComplete();
+
  private:
   friend class ComboboxTest;
   friend class TextfieldTest;
 
   // Sets the value of |disable_inactive_rendering_|. If the value changes,
   // both the NonClientView and WidgetDelegate are notified.
   void SetInactiveRenderingDisabled(bool value);
 
   // Persists the window's restored position and "show" state using the
   // window delegate.
@@ skipping 122 matching lines @@
   bool movement_disabled_;
 
   ScopedObserver<ui::NativeTheme, ui::NativeThemeObserver> observer_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_H_