text: // 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_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_TRACK_METRICS_HOST_H_
  #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_TRACK_METRICS_HOST_H_
  
  #include <map>
  #include <string>
  
  #include "base/time/time.h"
  #include "content/public/browser/browser_message_filter.h"
  
  namespace content {
  
  // Responsible for logging metrics about audio and video track
  // lifetimes. These are based on messages from the renderer that are
  // sent when tracks are created and destroyed. Unfortunately we can't
  // reliably log the lifetime metric in the renderer because that
  // process may be destroyed at any time by the fast shutdown path (see
  // RenderProcessHost::FastShutdownIfPossible).
  //
  // There is one instance of this class per render process.
  //
  // If the renderer process goes away without sending messages that
  // tracks were removed, this class instead infers that the tracks were
  // removed.
  class MediaStreamTrackMetricsHost
      : public BrowserMessageFilter {
   public:
    explicit MediaStreamTrackMetricsHost();
  
   protected:
    virtual ~MediaStreamTrackMetricsHost();
  
    // BrowserMessageFilter override.
    virtual bool OnMessageReceived(const IPC::Message& message,
                                   bool* message_was_ok) OVERRIDE;
  
   private:
    void OnAddTrack(uint64 id, bool is_audio, bool is_remote);
    void OnRemoveTrack(uint64 id);
  
    void ReportDuration(bool is_audio, base::TimeTicks start_time);
  
    // Keys are unique (per renderer) track IDs, values are pairs: A
    // boolean indicating whether the track is an audio track, and a
    // timestamp from when the track was created.
    typedef std::pair<bool, base::TimeTicks> IsAudioPlusTimestamp;
    typedef std::map<uint64, IsAudioPlusTimestamp> TrackMap;
    TrackMap tracks_;
  };
  
  }  // namespace content
  
  #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_TRACK_METRICS_HOST_H_
  