Make AudioDebugFileWriter::AudioFileWriter use a SequencedTaskRunner

media/audio/audio_debug_file_writer.h

 // Copyright 2015 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_FILE_WRITER_H_
 #define MEDIA_AUDIO_AUDIO_DEBUG_FILE_WRITER_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/files/file.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequence_checker.h"
+#include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
 #include "media/base/audio_parameters.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 class AudioBus;
 
 // Writes audio data to a 16 bit PCM WAVE file used for debugging purposes. All
 // operations are non-blocking.
@@ skipping 32 matching lines @@
   // the filename.
   virtual const base::FilePath::CharType* GetFileNameExtension();
 
  protected:
   const AudioParameters params_;
 
  private:
   class AudioFileWriter;
 
   // Deleter for AudioFileWriter.
-  struct OnThreadDeleter {
+  struct OnSequenceDeleter {
    public:
-    OnThreadDeleter();
-    OnThreadDeleter(const OnThreadDeleter& other);
-    OnThreadDeleter(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
-    ~OnThreadDeleter();
+    OnSequenceDeleter();
+    OnSequenceDeleter(OnSequenceDeleter&& other);
+    OnSequenceDeleter& operator=(const OnSequenceDeleter&);

[gab, 2017/05/18 22:11:21]

Actually you want the matching move assignment operator, not copy asssignment:

OnSequenceDeleter& operator= (OnSequenceDeleter &&)

[Sébastien Marchand, 2017/05/18 22:47:25]

Ha! Time for me to re learn C++11 and the move semantic.

+    OnSequenceDeleter(scoped_refptr<base::SequencedTaskRunner> task_runner);
+    ~OnSequenceDeleter();
     void operator()(AudioFileWriter* ptr) const;
 
    private:
-    scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+    scoped_refptr<base::SequencedTaskRunner> task_runner_;
   };
 
   using AudioFileWriterUniquePtr =
-      std::unique_ptr<AudioFileWriter, OnThreadDeleter>;
+      std::unique_ptr<AudioFileWriter, OnSequenceDeleter>;
 
   AudioFileWriterUniquePtr file_writer_;
   base::SequenceChecker client_sequence_checker_;
 
   // The task runner to do file output operations on.
   scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDebugFileWriter);
 };
 
 }  // namspace media
 
 #endif  // MEDIA_AUDIO_AUDIO_DEBUG_FILE_WRITER_H_