Remove no-longer-needed IsBusy...() stuff.

mojo/edk/system/data_pipe_producer_dispatcher.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 MOJO_EDK_SYSTEM_DATA_PIPE_PRODUCER_DISPATCHER_H_
 #define MOJO_EDK_SYSTEM_DATA_PIPE_PRODUCER_DISPATCHER_H_
 
 #include "mojo/edk/system/dispatcher.h"
 #include "mojo/edk/util/ref_ptr.h"
 #include "mojo/edk/util/thread_annotations.h"
@@ skipping 65 matching lines @@
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
                                 size_t* max_platform_handles) override
       MOJO_NOT_THREAD_SAFE;
   bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
       std::vector<platform::ScopedPlatformHandle>* platform_handles) override
       MOJO_NOT_THREAD_SAFE;
-  bool IsBusyNoLock() const override;
 
   // This will be null if closed.
   util::RefPtr<DataPipe> data_pipe_ MOJO_GUARDED_BY(mutex());
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(DataPipeProducerDispatcher);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_DATA_PIPE_PRODUCER_DISPATCHER_H_