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

content/browser/renderer_host/media/media_stream_track_metrics_host.cc

+// 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.
+
+#include "content/browser/renderer_host/media/media_stream_track_metrics_host.h"
+
+#include "base/metrics/histogram.h"
+#include "content/common/media/media_stream_track_metrics_host_messages.h"
+#include "content/public/browser/render_process_host.h"
+
+// We use a histogram with a maximum bucket of 16 hours to infinity
+// for track durations.
+#define UMA_HISTOGRAM_TIMES_16H(name, sample)                        \
+  UMA_HISTOGRAM_CUSTOM_TIMES(name, sample,                           \
+                             base::TimeDelta::FromMilliseconds(100), \
+                             base::TimeDelta::FromHours(16),         \
+                             50);
+
+namespace content {
+
+MediaStreamTrackMetricsHost::MediaStreamTrackMetricsHost(
+    RenderProcessHost* owner)
+    : BrowserMessageFilter(MediaStreamTrackMetricsHostMsgStart),
+      owner_(owner) {
+  owner_->AddObserver(this);
+}
+
+MediaStreamTrackMetricsHost::~MediaStreamTrackMetricsHost() {
+  owner_->RemoveObserver(this);
+
+  DCHECK(tracks_.empty());
+}
+
+bool MediaStreamTrackMetricsHost::OnMessageReceived(
+    const IPC::Message& message,
+    bool* message_was_ok) {
+  bool handled = true;
+
+  IPC_BEGIN_MESSAGE_MAP_EX(MediaStreamTrackMetricsHost,
+                           message,
+                           *message_was_ok)
+    IPC_MESSAGE_HANDLER(MediaStreamTrackMetricsHost_AddTrack, OnAddTrack)
+    IPC_MESSAGE_HANDLER(MediaStreamTrackMetricsHost_RemoveTrack, OnRemoveTrack)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP_EX()
+
+  return handled;
+}
+
+void MediaStreamTrackMetricsHost::RenderProcessExited(
+    RenderProcessHost* host,
+    base::ProcessHandle handle,
+    base::TerminationStatus status,
+    int exit_code) {
+  DCHECK_EQ(owner_, host);
+
+  // Our render process has exited. We won't receive any more IPC
+  // messages from it. Assume all tracks ended now.
+  for (TrackMap::iterator it = tracks_.begin();
+       it != tracks_.end();
+       ++it) {
+    IsAudioPlusTimestamp& audio_and_timestamp = it->second;
+    ReportDuration(audio_and_timestamp.first, audio_and_timestamp.second);
+  }
+  tracks_.clear();
+}
+
+void MediaStreamTrackMetricsHost::OnAddTrack(uint64 id,
+                                             bool is_audio,
+                                             bool is_remote) {
+  DCHECK(tracks_.find(id) == tracks_.end());
+  DCHECK(is_remote);  // Always the case for now.
+
+  tracks_[id] = IsAudioPlusTimestamp(is_audio, base::TimeTicks::Now());
+}
+
+void MediaStreamTrackMetricsHost::OnRemoveTrack(uint64 id) {
+  DCHECK(tracks_.find(id) != tracks_.end());
+
+  IsAudioPlusTimestamp& info = tracks_[id];
+  ReportDuration(info.first, info.second);

[perkj_chrome, 2014/03/12 10:21:34]

use |is_remote| ? or add a todo to do it later.

+  tracks_.erase(id);
+}
+
+void MediaStreamTrackMetricsHost::ReportDuration(bool is_audio,
+                                                 base::TimeTicks start_time) {
+  base::TimeDelta duration = start_time - base::TimeTicks::Now();
+  if (is_audio) {
+    UMA_HISTOGRAM_TIMES_16H("WebRTC.ReceivedAudioTrackDuration", duration);
+  } else {
+    UMA_HISTOGRAM_TIMES_16H("WebRTC.ReceivedVideoTrackDuration", duration);
+  }
+}
+
+}  // namespace content