Remove unused flush operation from Chromium audio.

content/common/media/audio_messages.h

 // Copyright (c) 2012 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.
 
 // IPC messages for the audio.
 // Multiply-included message file, hence no include guard.
 
 #include "base/basictypes.h"
 #include "base/shared_memory.h"
 #include "base/sync_socket.h"
@@ skipping 104 matching lines @@
                      int /* stream_id */)
 
 // Start recording the audio input stream specified by stream_id.
 IPC_MESSAGE_CONTROL1(AudioInputHostMsg_RecordStream,
                      int /* stream_id */)
 
 // Pause the audio stream specified by stream_id.
 IPC_MESSAGE_CONTROL1(AudioHostMsg_PauseStream,
                      int /* stream_id */)
 
-// Discard all buffered audio data for the specified audio stream.
-IPC_MESSAGE_CONTROL1(AudioHostMsg_FlushStream,
-                     int /* stream_id */)
-
 // Close an audio stream specified by stream_id.
 IPC_MESSAGE_CONTROL1(AudioHostMsg_CloseStream,
                      int /* stream_id */)
 
 // Close an audio input stream specified by stream_id.
 IPC_MESSAGE_CONTROL1(AudioInputHostMsg_CloseStream,
                      int /* stream_id */)
 
 // Set audio volume of the stream specified by stream_id.
 // TODO(hclam): change this to vector if we have channel numbers other than 2.
 IPC_MESSAGE_CONTROL2(AudioHostMsg_SetVolume,
                      int /* stream_id */,
                      double /* volume */)
 
 // Set audio volume of the input stream specified by stream_id.
 IPC_MESSAGE_CONTROL2(AudioInputHostMsg_SetVolume,
                      int /* stream_id */,
                      double /* volume */)