[Chromecast] Implement new volume control API

chromecast/media/cma/backend/alsa/media_pipeline_backend_alsa.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 CHROMECAST_MEDIA_CMA_BACKEND_ALSA_MEDIA_PIPELINE_BACKEND_ALSA_H_
 #define CHROMECAST_MEDIA_CMA_BACKEND_ALSA_MEDIA_PIPELINE_BACKEND_ALSA_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "chromecast/public/media/media_pipeline_backend.h"
 #include "chromecast/public/media/media_pipeline_device_params.h"
+#include "chromecast/public/volume_control.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace chromecast {
 namespace media {
 class AudioDecoderAlsa;
 class VideoDecoderNull;
 
@@ skipping 10 matching lines @@
   bool Initialize() override;
   bool Start(int64_t start_pts) override;
   void Stop() override;
   bool Pause() override;
   bool Resume() override;
   bool SetPlaybackRate(float rate) override;
   int64_t GetCurrentPts() override;
 
   bool Primary() const;
   std::string DeviceId() const;
+  AudioContentType ContentType() const;
   const scoped_refptr<base::SingleThreadTaskRunner>& GetTaskRunner() const;
 
  private:
   // State variable for DCHECKing caller correctness.
   enum State {
     kStateUninitialized,
     kStateInitialized,
     kStatePlaying,
     kStatePaused,
   };
   State state_;
 
   const MediaPipelineDeviceParams params_;
   std::unique_ptr<VideoDecoderNull> video_decoder_;
   std::unique_ptr<AudioDecoderAlsa> audio_decoder_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaPipelineBackendAlsa);
 };
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_CMA_BACKEND_ALSA_MEDIA_PIPELINE_BACKEND_ALSA_H_