Privitize WaitTillDataReady() and DataReady().

media/audio/win/waveout_output_win.cc

 // 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.
 
 #include "media/audio/win/waveout_output_win.h"
 
 #include <windows.h>
 #include <mmsystem.h>
 #pragma comment(lib, "winmm.lib")
 
@@ skipping 186 matching lines @@
     waiting_handle_ = NULL;
     return;
   }
 
   state_ = PCMA_PLAYING;
 
   // Queue the buffers.
   pending_bytes_ = 0;
   for (int ix = 0; ix != num_buffers_; ++ix) {
     WAVEHDR* buffer = GetBuffer(ix);
-    // Caller waits for 1st packet to become available, but not for others,
-    // so we wait for them here.
-    if (ix != 0)
-      callback_->WaitTillDataReady();
     QueueNextPacket(buffer);  // Read more data.
     pending_bytes_ += buffer->dwBufferLength;
   }
 
   // From now on |pending_bytes_| would be accessed by callback thread.
   // Most likely waveOutPause() or waveOutRestart() has its own memory barrier,
   // but issuing our own is safer.
   base::subtle::MemoryBarrier();
 
   MMRESULT result = ::waveOutPause(waveout_);
@@ skipping 115 matching lines @@
   if (callback_)
     callback_->OnError(this);
 }
 
 void PCMWaveOutAudioOutputStream::QueueNextPacket(WAVEHDR *buffer) {
   DCHECK_EQ(channels_, format_.Format.nChannels);
   // Call the source which will fill our buffer with pleasant sounds and
   // return to us how many bytes were used.
   // TODO(fbarchard): Handle used 0 by queueing more.
 
-  // HACK: Yield if Read() is called too often.  On older platforms which are
-  // still using the WaveOut backend, we run into synchronization issues where
-  // the renderer has not finished filling the shared memory when Read() is
-  // called.  Reading too early will lead to clicks and pops.  See issues:
-  // http://crbug.com/161307 and http://crbug.com/61022
-  callback_->WaitTillDataReady();
-
   // TODO(sergeyu): Specify correct hardware delay for AudioBuffersState.
   int frames_filled = callback_->OnMoreData(
       audio_bus_.get(), AudioBuffersState(pending_bytes_, 0));
   uint32 used = frames_filled * audio_bus_->channels() *
       format_.Format.wBitsPerSample / 8;
 
   if (used <= buffer_size_) {
     // Note: If this ever changes to output raw float the data must be clipped
     // and sanitized since it may come from an untrusted source such as NaCl.
     audio_bus_->Scale(volume_);
@@ skipping 49 matching lines @@
                                        buffer,
                                        sizeof(WAVEHDR));
       if (result != MMSYSERR_NOERROR)
         stream->HandleError(result);
       stream->pending_bytes_ += buffer->dwBufferLength;
     }
   }
 }
 
 }  // namespace media