events: Remove ability to terminate a nested message-loop from the event-source.

ui/events/platform/platform_event_source.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_EVENTS_PLATFORM_PLATFORM_EVENT_SOURCE_H_
 #define UI_EVENTS_PLATFORM_PLATFORM_EVENT_SOURCE_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 52 matching lines @@
   // dispatcher installed using |OverrideDispatcher()|, then that dispatcher
   // receives the event first. |POST_DISPATCH_QUIT_LOOP| flag is set in the
   // returned value if the event-source should stop dispatching events at the
   // current message-loop iteration.
   virtual uint32_t DispatchEvent(PlatformEvent platform_event);
 
  private:
   friend class ScopedEventDispatcher;
   static PlatformEventSource* instance_;
 
+  // Called to indicate that the source should stop dispatching the current
+  // stream of events and wait until the next iteration of the message-loop to
+  // dispatch the rest of the events.
+  virtual void StopCurrentEventStream();
+
   // This is invoked when the list of dispatchers changes (i.e. a new dispatcher
   // is added, or a dispatcher is removed).
   virtual void OnDispatcherListChanged();
 
   void OnOverriddenDispatcherRestored();
 
   // Use an ObserverList<> instead of an std::vector<> to store the list of
   // dispatchers, so that adding/removing dispatchers during an event dispatch
   // is well-defined.
   typedef ObserverList<PlatformEventDispatcher> PlatformEventDispatcherList;
   PlatformEventDispatcherList dispatchers_;
   PlatformEventDispatcher* overridden_dispatcher_;
 
   // Used to keep track of whether the current override-dispatcher has been
   // reset and a previous override-dispatcher has been restored.
   bool overridden_dispatcher_restored_;
 
   ObserverList<PlatformEventObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformEventSource);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_PLATFORM_PLATFORM_EVENT_SOURCE_H_