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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_DISPATCHER_H
      6 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_DISPATCHER_H
      7 
      8 #include "base/base_export.h"
      9 #include "base/event_types.h"
     10 
     11 namespace base {
     12 
     13 // Dispatcher is used during a nested invocation of Run to dispatch events when
     14 // |RunLoop(dispatcher).Run()| is used.  If |RunLoop().Run()| is invoked,
     15 // MessageLoop does not dispatch events (or invoke TranslateMessage), rather
     16 // every message is passed to Dispatcher's Dispatch method for dispatch. It is
     17 // up to the Dispatcher whether or not to dispatch the event.
     18 //
     19 // The nested loop is exited by either posting a quit, or returning false
     20 // from Dispatch.
     21 class BASE_EXPORT MessagePumpDispatcher {
     22  public:
     23   virtual ~MessagePumpDispatcher() {}
     24 
     25   // Dispatches the event. If true is returned processing continues as
     26   // normal. If false is returned, the nested loop exits immediately.
     27   virtual bool Dispatch(const NativeEvent& event) = 0;
     28 };
     29 
     30 }  // namespace base
     31 
     32 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_DISPATCHER_H
     33