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

content/renderer/media/remote_media_stream_impl.cc

 // Copyright (c) 2013 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.
 
 #include "content/renderer/media/remote_media_stream_impl.h"
 
 #include <string>
 
 #include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
+#include "content/common/media/media_track_lifetime_metrics_messages.h"
 #include "content/renderer/media/media_stream.h"
 #include "content/renderer/media/media_stream_dependency_factory.h"
+#include "content/renderer/render_thread_impl.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace content {
 
 // RemoteMediaStreamTrackObserver is responsible for listening on change
 // notification on a remote webrtc MediaStreamTrack and notify WebKit.
 class RemoteMediaStreamTrackObserver
     : NON_EXPORTED_BASE(public webrtc::ObserverInterface),
       NON_EXPORTED_BASE(public base::NonThreadSafe) {
  public:
@@ skipping 50 matching lines @@
 
 namespace content {
 
 RemoteMediaStreamTrackObserver::RemoteMediaStreamTrackObserver(
     webrtc::MediaStreamTrackInterface* webrtc_track,
     const blink::WebMediaStreamTrack& webkit_track)
     : state_(webrtc_track->state()),
       webrtc_track_(webrtc_track),
       webkit_track_(webkit_track) {
   webrtc_track->RegisterObserver(this);
+
+  // We need to mirror the lifetime state for tracks to the browser
+  // process so that the duration of tracks can be accurately
+  // reported, because of RenderProcessHost::FastShutdownIfPossible,
+  // which in many cases will simply kill the renderer process.
+  RenderThreadImpl::current()->Send(new MediaTrackLifetimeMetrics_AddTrack(

[perkj_chrome, 2014/03/11 08:05:21]

Can we do this in a virtual method instead so I can write a unit test for the
track observer that can't deal whith the static render thread and ipc messages?
I am refactoring this class currently to support having the remote video tracks
be a source to the chrome tracks as discussed.

I can do that in my cl if you think that is the correct approach.

[Jói, 2014/03/11 17:36:33]

Sure, sounds good.

+      webkit_track_.id().utf8(),

[perkj_chrome, 2014/03/11 08:05:21]

To make this a bit harder - the same track can theoretically be received in
multiple mediastreams on the same PeerConnection. They will have the same id.

[Jói, 2014/03/11 17:36:33]

I'm now using the MediaStream ID plus the track ID.

+      webkit_track_.source().type() == blink::WebMediaStreamSource::TypeAudio));
 }
 
 RemoteMediaStreamTrackObserver::~RemoteMediaStreamTrackObserver() {
+  RenderThreadImpl::current()->Send(new MediaTrackLifetimeMetrics_RemoveTrack(

[perkj_chrome, 2014/03/11 08:05:21]

dito

[Jói, 2014/03/11 17:36:33]

Done.

+      webkit_track_.id().utf8()));
+
   webrtc_track_->UnregisterObserver(this);
 }
 
 void RemoteMediaStreamTrackObserver::OnChanged() {
   DCHECK(CalledOnValidThread());
 
   webrtc::MediaStreamTrackInterface::TrackState state = webrtc_track_->state();
   if (state == state_)
     return;
 
@@ skipping 115 matching lines @@
       InitializeWebkitTrack(*it, &new_track,
                             blink::WebMediaStreamSource::TypeVideo);
       video_track_observers_.push_back(
           new RemoteMediaStreamTrackObserver(*it, new_track));
       webkit_stream_.addTrack(new_track);
     }
   }
 }
 
 }  // namespace content