Dispatch a synthetic mouse exit to the widget handling mouse events when a widget grabs capture

ui/aura/window_event_dispatcher.h

 // Copyright 2014 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_AURA_WINDOW_EVENT_DISPATCHER_H_
 #define UI_AURA_WINDOW_EVENT_DISPATCHER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 56 matching lines @@
   // types (although the latter is currently a no-op).
   void RepostEvent(const ui::LocatedEvent& event);
 
   // Invoked when the mouse events get enabled or disabled.
   void OnMouseEventsEnableStateChanged(bool enabled);
 
   void DispatchCancelModeEvent();
 
   // Dispatches a ui::ET_MOUSE_EXITED event at |point|.
   // TODO(beng): needed only for WTH::OnCursorVisibilityChanged().
-  void DispatchMouseExitAtPoint(const gfx::Point& point);
+  ui::EventDispatchDetails DispatchMouseExitAtPoint(
+      const gfx::Point& point) WARN_UNUSED_RESULT;
 
   // Gesture Recognition -------------------------------------------------------
 
   // When a touch event is dispatched to a Window, it may want to process the
   // touch event asynchronously. In such cases, the window should consume the
   // event during the event dispatch. Once the event is properly processed, the
   // window should let the WindowEventDispatcher know about the result of the
   // event processing, so that gesture events can be properly created and
   // dispatched.
   void ProcessedTouchEvent(ui::TouchEvent* event,
@@ skipping 168 matching lines @@
 
   // Used to schedule DispatchHeldEvents() when |move_hold_count_| goes to 0.
   base::WeakPtrFactory<WindowEventDispatcher> held_event_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowEventDispatcher);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_EVENT_DISPATCHER_H_