Audio output debug recording.

media/audio/audio_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_FILE_WRITER_H_
 #define MEDIA_AUDIO_AUDIO_FILE_WRITER_H_
 
 #include <memory>
 
+#include "base/callback_forward.h"
+
+namespace base {
+class FilePath;
+}
+
 namespace media {
 
 class AudioBus;
+class AudioParameters;
 
 // A writer interface used for writing audio data to file for debugging
 // purposes.
 class AudioFileWriter {
  public:
   virtual ~AudioFileWriter() {}
 
   // Must be called before calling Write() for the first time after creation or
   // Stop() call. Can be called on any sequence; Write() and Stop() must be
   // called on the same sequence as Start().
   virtual void Start(const base::FilePath& file) = 0;
 
   // Must be called to finish recording. Each call to Start() requires a call to
   // Stop(). Will be automatically called on destruction.
   virtual void Stop() = 0;
 
   // Write |data| to file.
   virtual void Write(std::unique_ptr<AudioBus> data) = 0;
 
   // Returns true if Write() call scheduled at this point will most likely write
   // data to the file, and false if it most likely will be a no-op. The result
   // may be ambigulous if Start() or Stop() is executed at the moment. Can be
   // called from any sequence.
   virtual bool WillWrite() = 0;
 };
 
+// Used for creating an AudioFileWriter.
+using CreateAudioFileWriterCallback =
+    base::RepeatingCallback<std::unique_ptr<AudioFileWriter>(
+        const AudioParameters&)>;
+
 }  // namspace media
 
 #endif  // MEDIA_AUDIO_AUDIO_FILE_WRITER_H_