Always clear callback after WaveOut Stop().

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 230 matching lines @@
 //             of all currently playing streams. Then you don't have to wait
 //             till all callbacks are completed. Of course access to singleton
 //             should be under its own lock, and checking the liveness and
 //             acquiring the lock on stream should be done atomically.
 void PCMWaveOutAudioOutputStream::Stop() {
   if (state_ != PCMA_PLAYING)
     return;
   state_ = PCMA_STOPPING;
   base::subtle::MemoryBarrier();
 
-  // Stop watching for buffer event, wait till all the callbacks are complete.
-  // Should be done before ::waveOutReset() call to avoid race condition when
-  // callback that is currently active and already checked that stream is still
-  // being played calls ::waveOutWrite() after ::waveOutReset() returns, later
-  // causing ::waveOutClose() to fail with WAVERR_STILLPLAYING.
-  // TODO(enal): that delays actual stopping of playback. Alternative can be
-  //             to call ::waveOutReset() twice, once before
-  //             ::UnregisterWaitEx() and once after.
+  // Stop watching for buffer event, waits until outstanding callbacks finish.
   if (waiting_handle_) {
-    if (!::UnregisterWaitEx(waiting_handle_, INVALID_HANDLE_VALUE)) {
-      state_ = PCMA_PLAYING;
-      HandleError(MMSYSERR_ERROR);
-      return;
-    }
+    if (!::UnregisterWaitEx(waiting_handle_, INVALID_HANDLE_VALUE))
+      HandleError(::GetLastError());
     waiting_handle_ = NULL;
   }
 
   // Stop playback.
   MMRESULT res = ::waveOutReset(waveout_);
-  if (res != MMSYSERR_NOERROR) {
-    state_ = PCMA_PLAYING;
+  if (res != MMSYSERR_NOERROR)
     HandleError(res);
-    return;
-  }
 
   // Wait for lock to ensure all outstanding callbacks have completed.
   base::AutoLock auto_lock(lock_);
 
   // waveOutReset() leaves buffers in the unpredictable state, causing
   // problems if we want to close, release, or reuse them. Fix the states.
-  for (int ix = 0; ix != num_buffers_; ++ix) {
+  for (int ix = 0; ix != num_buffers_; ++ix)
     GetBuffer(ix)->dwFlags = WHDR_PREPARED;
-  }
 
   // Don't use callback after Stop().
   callback_ = NULL;
 
   state_ = PCMA_READY;
 }
 
 // We can Close in any state except that trying to close a stream that is
 // playing Windows generates an error. We cannot propagate it to the source,
 // as callback_ is set to NULL. Just print it and hope somebody somehow
@@ skipping 107 matching lines @@
                                        buffer,
                                        sizeof(WAVEHDR));
       if (result != MMSYSERR_NOERROR)
         stream->HandleError(result);
       stream->pending_bytes_ += buffer->dwBufferLength;
     }
   }
 }
 
 }  // namespace media