Avoid hitting the thread check when WebRtcAudioRenderer is going away.

content/renderer/media/media_stream_audio_processor.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 "content/renderer/media/media_stream_audio_processor.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "content/public/common/content_switches.h"
 #include "content/renderer/media/media_stream_audio_processor_options.h"
@@ skipping 200 matching lines @@
   base::subtle::Release_Store(&render_delay_ms_, audio_delay_milliseconds);
 
   InitializeRenderConverterIfNeeded(sample_rate, audio_bus->channels(),
                                     audio_bus->frames());
 
   render_converter_->Push(audio_bus);
   while (render_converter_->Convert(&render_frame_))
     audio_processing_->AnalyzeReverseStream(&render_frame_);
 }
 
+void MediaStreamAudioProcessor::OnPlayoutDataSourceChanged() {
+  DCHECK(main_thread_checker_.CalledOnValidThread());
+  // There is no need to hold a lock here since the caller guarantees that
+  // there is no more OnPlayoutData() callback on the render thread.
+  render_thread_checker_.DetachFromThread();
+  render_converter_.reset();
+}
+
 void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
     const blink::WebMediaConstraints& constraints, int effects) {
   DCHECK(!audio_processing_);
   if (!CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableAudioTrackProcessing)) {
     return;
   }
 
   RTCMediaConstraints native_constraints(constraints);
   ApplyFixedAudioConstraints(&native_constraints);
@@ skipping 200 matching lines @@
   if (!audio_processing_.get())
     return;
 
   if (playout_data_source_)
     playout_data_source_->RemovePlayoutSink(this);
 
   audio_processing_.reset();
 }
 
 }  // namespace content