MediaCaptureFromElement: add support for audio captureStream().

media/blink/webaudiosourceprovider_impl.cc

 // Copyright 2013 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/blink/webaudiosourceprovider_impl.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 215 matching lines @@
 
   sink_->Initialize(params, tee_filter_.get());
 
   if (!set_format_cb_.is_null())
     base::ResetAndReturn(&set_format_cb_).Run();
 }
 
 void WebAudioSourceProviderImpl::SetCopyAudioCallback(
     const CopyAudioCB& callback) {
   DCHECK(!callback.is_null());
+
+  // Use |sink_lock_| to protect |tee_filter_| too since they go in lockstep.
+  base::AutoLock auto_lock(sink_lock_);
+
   DCHECK(tee_filter_);
   tee_filter_->set_copy_audio_bus_callback(callback);
 }
 
 void WebAudioSourceProviderImpl::ClearCopyAudioCallback() {
   DCHECK(tee_filter_);
   tee_filter_->set_copy_audio_bus_callback(CopyAudioCB());
 }
 
+int WebAudioSourceProviderImpl::RenderForTesting(AudioBus* audio_bus) {
+  return tee_filter_->Render(audio_bus, 0, 0);
+}
+
 void WebAudioSourceProviderImpl::OnSetFormat() {
   base::AutoLock auto_lock(sink_lock_);
   if (!client_)
     return;
 
   // Inform Blink about the audio stream format.
   client_->setFormat(tee_filter_->channels(), tee_filter_->sample_rate());
 }
 
-int WebAudioSourceProviderImpl::RenderForTesting(AudioBus* audio_bus) {
-  return tee_filter_->Render(audio_bus, 0, 0);
-}
-
 int WebAudioSourceProviderImpl::TeeFilter::Render(AudioBus* audio_bus,
                                                   uint32_t delay_milliseconds,
                                                   uint32_t frames_skipped) {
   const int num_rendered_frames =
       renderer_->Render(audio_bus, delay_milliseconds, frames_skipped);
 
   if (!copy_audio_bus_callback_.is_null()) {
     std::unique_ptr<AudioBus> bus_copy =
         AudioBus::Create(audio_bus->channels(), audio_bus->frames());
     audio_bus->CopyTo(bus_copy.get());
     copy_audio_bus_callback_.Run(std::move(bus_copy), delay_milliseconds,
                                  sample_rate_);
   }
 
   return num_rendered_frames;
 }
 
 void WebAudioSourceProviderImpl::TeeFilter::OnRenderError() {
   renderer_->OnRenderError();
 }
 
 }  // namespace media