Make AudioDebugFileWriter create its own file worker thread.

media/audio/audio_debug_recording_helper.h

 // Copyright 2017 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.
 
 #ifndef MEDIA_AUDIO_AUDIO_DEBUG_RECORDING_HELPER_H_
 #define MEDIA_AUDIO_AUDIO_DEBUG_RECORDING_HELPER_H_
 
 #include <memory>
 
 #include "base/atomicops.h"
@@ skipping 35 matching lines @@
 // could be skipped then. Currently we have
 // soundcard thread -> control thread -> file thread,
 // and with the merge we should be able to do
 // soundcard thread -> file thread.
 class MEDIA_EXPORT AudioDebugRecordingHelper
     : public NON_EXPORTED_BASE(AudioDebugRecorder) {
  public:
   AudioDebugRecordingHelper(
       const AudioParameters& params,
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
       base::OnceClosure on_destruction_closure);
   ~AudioDebugRecordingHelper() override;
 
   // Enable debug recording. The create callback is first run to create an
   // AudioDebugFileWriter.
   virtual void EnableDebugRecording(const base::FilePath& file_name);
 
   // Disable debug recording. The AudioDebugFileWriter is destroyed.
   virtual void DisableDebugRecording();
 
   // AudioDebugRecorder implementation. Can be called on any thread.
   void OnData(const AudioBus* source) override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(AudioDebugRecordingHelperTest, EnableDisable);
   FRIEND_TEST_ALL_PREFIXES(AudioDebugRecordingHelperTest, OnData);
 
   // Writes debug data to |debug_writer_|.
   void DoWrite(std::unique_ptr<media::AudioBus> data);
 
   // Creates an AudioDebugFileWriter. Overridden by test.
   virtual std::unique_ptr<AudioDebugFileWriter> CreateAudioDebugFileWriter(
-      const AudioParameters& params,
-      scoped_refptr<base::SingleThreadTaskRunner> file_task_runner);
+      const AudioParameters& params);
 
   const AudioParameters params_;
   std::unique_ptr<AudioDebugFileWriter> debug_writer_;
 
   // Used as a flag to indicate if recording is enabled, accessed on different
   // threads.
   base::subtle::Atomic32 recording_enabled_;
 
   // The task runner for accessing |debug_writer_|.
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
-  // Task runner passed to |debug_writer_| to do file output operations on.
-  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
-
   // Runs in destructor if set.
   base::OnceClosure on_destruction_closure_;
 
   base::WeakPtrFactory<AudioDebugRecordingHelper> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(AudioDebugRecordingHelper);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_DEBUG_RECORDING_HELPER_H_