Implement MediaStreamTrack contentHint skeleton.

content/renderer/media/media_stream_track.h

 // Copyright 2014 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 CONTENT_RENDERER_MEDIA_MEDIA_STREAM_TRACK_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_TRACK_H_
 
+#include <string>
+
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/content_export.h"
 #include "media/base/audio_parameters.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
 
 namespace content {
 
 // MediaStreamTrack is a Chrome representation of blink::WebMediaStreamTrack.
 // It is owned by blink::WebMediaStreamTrack as
 // blink::WebMediaStreamTrack::ExtraData.
 class CONTENT_EXPORT MediaStreamTrack
     : NON_EXPORTED_BASE(public blink::WebMediaStreamTrack::TrackData) {
  public:
   explicit MediaStreamTrack(bool is_local_track);
   ~MediaStreamTrack() override;
 
   static MediaStreamTrack* GetTrack(const blink::WebMediaStreamTrack& track);
 
   virtual void SetEnabled(bool enabled) = 0;
 
+  virtual void SetContentHint(
+      blink::WebMediaStreamTrack::ContentHintType content_hint) = 0;
+
   virtual void Stop() = 0;
 
   // TODO(hta): Make method pure virtual when all tracks have the method.
   void getSettings(blink::WebMediaStreamTrack::Settings& settings) override {}
 
   bool is_local_track() const { return is_local_track_; }
 
  protected:
   const bool is_local_track_;
 
   // Used to DCHECK that we are called on Render main Thread.
   base::ThreadChecker main_render_thread_checker_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MediaStreamTrack);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_TRACK_H_