base: Cleanup class/struct forward declarations

base/message_loop/incoming_task_queue.h

 // Copyright 2013 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 BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_
 #define BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_
 
 #include "base/base_export.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/pending_task.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/read_write_lock.h"
 #include "base/time/time.h"
 
 namespace base {
 
 class MessageLoop;
-class WaitableEvent;
 
 namespace internal {
 
 // Implements a queue of tasks posted to the message loop running on the current
 // thread. This class takes care of synchronizing posting tasks from different
 // threads and together with MessageLoop ensures clean shutdown.
 class BASE_EXPORT IncomingTaskQueue
     : public RefCountedThreadSafe<IncomingTaskQueue> {
  public:
   explicit IncomingTaskQueue(MessageLoop* message_loop);
@@ skipping 76 matching lines @@
   // False until StartScheduling() is called.
   bool is_ready_for_scheduling_;
 
   DISALLOW_COPY_AND_ASSIGN(IncomingTaskQueue);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_