On 1180 (M21): Always use non-low-latency (wave out) audio for Pepper plugins on Windows.

src/content/renderer/pepper/pepper_platform_audio_output_impl.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 "content/renderer/pepper/pepper_platform_audio_output_impl.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop_proxy.h"
 #include "build/build_config.h"
@@ skipping 95 matching lines @@
     int sample_rate,
     int frames_per_buffer,
     webkit::ppapi::PluginDelegate::PlatformAudioOutputClient* client) {
   DCHECK(client);
   // Make sure we don't call init more than once.
   DCHECK_EQ(0, stream_id_);
 
   client_ = client;
 
   media::AudioParameters::Format format;
+#if defined(OS_WIN)
+  // For Chrome 21 on Windows, avoid the low-latency (WASAPI) path for the sake
+  // of Pepper Flash. Currently, the WASAPI path will fail silently for, e.g.,
+  // 5.1/7.1 sound. (Flash always requests 44.1 kHz anyways, so it's already
+  // using the non-low-latency (wave-out) path on any system that's configured
+  // for 48 kHz.)
+  format = media::AudioParameters::AUDIO_PCM_LINEAR;
+#else
   const int kMaxFramesForLowLatency = 2048;
   // Use the low latency back end if the client request is compatible, and
   // the sample count is low enough to justify using AUDIO_PCM_LOW_LATENCY.
   if (sample_rate == audio_hardware::GetOutputSampleRate() &&
       frames_per_buffer <= kMaxFramesForLowLatency &&
       frames_per_buffer % audio_hardware::GetOutputBufferSize() == 0) {
     format = media::AudioParameters::AUDIO_PCM_LOW_LATENCY;
   } else {
     format = media::AudioParameters::AUDIO_PCM_LINEAR;
   }
+#endif
 
   media::AudioParameters params(format, CHANNEL_LAYOUT_STEREO, sample_rate, 16,
                                 frames_per_buffer);
 
   ChildProcess::current()->io_message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&PepperPlatformAudioOutputImpl::InitializeOnIOThread,
                  this, params));
   return true;
 }
@@ skipping 21 matching lines @@
 
   filter_->Send(new AudioHostMsg_CloseStream(stream_id_));
   filter_->RemoveDelegate(stream_id_);
   stream_id_ = 0;
 
   Release();  // Release for the delegate, balances out the reference taken in
               // PepperPluginDelegateImpl::CreateAudio.
 }
 
 }  // namespace content