Increase Windows XP hardware buffer size to 4096.

media/audio/win/waveout_output_win.cc

Index: media/audio/win/waveout_output_win.cc
diff --git a/media/audio/win/waveout_output_win.cc b/media/audio/win/waveout_output_win.cc
index 12b4251d5ef671b11a2203bc2ee903e8f51792d9..5e56169a4db67d213a21e086f34777681de1209e 100644
--- a/media/audio/win/waveout_output_win.cc
+++ b/media/audio/win/waveout_output_win.cc
@@ -278,6 +278,9 @@ void PCMWaveOutAudioOutputStream::Stop() {
     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) {