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

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index bc3f91473dd19de5175b0b939a69341424b7a329..c6e7b48cd4c4ec42e412675b9cb8c19034a6b72a 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -793,6 +793,10 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // TODO(beng): remove once we fold those objects onto this one.
   void DestroyRootView();
 
+  // Notification that the drag performed by RunShellDrag() has completed.
+  // Default implementation does nothing.
+  virtual void OnDragComplete();

[sky, 2014/07/11 17:45:34]

You should move the code in MenuController::StartDrag so that state is set
correctly if a drag is initiated outside of the menu code. I believe this means
adding a method like OnDragWillStart() here having MenuHost override and forward
to MenuController. MenuController's OnDragWillStart would set drag_in_progress_.
A similar flow should happen at the end of the drag to either reset capture or
close menus.

[Devlin, 2014/07/11 18:43:51]

Done (though not much of the code in StartDrag() is relevant, since the drag is
initiated and handled through the other View).

[sky, 2014/07/11 19:15:20]

I wanted to make sure the state (which you're right, is only one boolean) is set
consistently for both cases. That's why moving to the method that is always
invoked is ideal.

[Devlin, 2014/07/11 20:28:15]

Yep, makes a lot of sense. :)  Just wanted to make sure that the only state that
applied was the bool, and that I wasn't missing something.

+
  private:
   friend class ComboboxTest;
   friend class TextfieldTest;