Add metrics to track the duration of tracks received over a PeerConnection.

content/browser/renderer_host/media/media_stream_track_metrics_host.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_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_TRACK_METRICS_HOST_H_

[perkj_chrome, 2014/03/12 07:12:40]

nit : git mv is the reviewers friend I think.Or lowering the comparison bar when
uploading the file.

[Jói, 2014/03/12 08:50:04]

I used git mv, indirectly. There are two problems:

a) git mv is just git rm + mv + git add, and it does nothing to track moves. git
only guesses at moves based on similarity of files.

b) These are actually new files, from the source control system point of view.
Rietveld does not try (AFAIK) to show you between-file deltas when files get
moved to a new location between patch sets.

I tried reuploading with --similarity=30, but it makes no difference, because of
(b) I'm guessing.

+#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"
+#include "content/public/browser/render_process_host_observer.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 RenderProcessHostObserver {
+ public:
+  explicit MediaStreamTrackMetricsHost(RenderProcessHost* owner);
+
+ protected:
+  virtual ~MediaStreamTrackMetricsHost();
+
+  // BrowserMessageFilter override.
+  virtual bool OnMessageReceived(const IPC::Message& message,
+                                 bool* message_was_ok) OVERRIDE;
+
+  // RenderProcessHostObserver override.
+  virtual void RenderProcessExited(RenderProcessHost* host,
+                                   base::ProcessHandle handle,
+                                   base::TerminationStatus status,
+                                   int exit_code) OVERRIDE;
+
+ private:
+  void OnAddTrack(const std::string& id, bool is_audio, bool is_remote);
+  void OnRemoveTrack(const std::string& id);
+
+  void ReportDuration(bool is_audio, base::TimeTicks start_time);
+
+  // Keys are 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<std::string, IsAudioPlusTimestamp> TrackMap;
+  TrackMap tracks_;
+
+  // Non-owning pointer.
+  RenderProcessHost* owner_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_TRACK_METRICS_HOST_H_