TrackMediaInfoMap added.

This maps, in both directions, [Audio/Video]TrackInterface with
[Voice/Video][Sender/Receiver]Info.

This mapping is necessary for RTCStatsCollector to know the relationship
between RTCMediaStreamTrackStats and RTC[In/Out]boundRTPStreamStats, and
to be able to collect several RTCMediaStreamTrackStats stats.

BUG=webrtc:6757, chromium:659137, chromium:657854, chromium:627816

Review-Url: https://codereview.webrtc.org/2611983002
Cr-Commit-Position: refs/heads/master@{#16090}
diff --git a/webrtc/api/BUILD.gn b/webrtc/api/BUILD.gn
index 7c5e302..149fd51 100644
--- a/webrtc/api/BUILD.gn
+++ b/webrtc/api/BUILD.gn
@@ -101,6 +101,8 @@
     "statstypes.cc",
     "statstypes.h",
     "streamcollection.h",
+    "trackmediainfomap.cc",
+    "trackmediainfomap.h",
     "videocapturertracksource.cc",
     "videocapturertracksource.h",
     "videosourceproxy.h",
@@ -254,12 +256,15 @@
       "test/fakevideotrackrenderer.h",
       "test/mock_datachannel.h",
       "test/mock_peerconnection.h",
+      "test/mock_rtpreceiver.h",
+      "test/mock_rtpsender.h",
       "test/mock_webrtcsession.h",
       "test/mockpeerconnectionobservers.h",
       "test/peerconnectiontestwrapper.cc",
       "test/peerconnectiontestwrapper.h",
       "test/rtcstatsobtainer.h",
       "test/testsdpstrings.h",
+      "trackmediainfomap_unittest.cc",
       "videocapturertracksource_unittest.cc",
       "videotrack_unittest.cc",
       "webrtcsdp_unittest.cc",
diff --git a/webrtc/api/test/mock_rtpreceiver.h b/webrtc/api/test/mock_rtpreceiver.h
new file mode 100644
index 0000000..25f5c28
--- /dev/null
+++ b/webrtc/api/test/mock_rtpreceiver.h
@@ -0,0 +1,34 @@
+/*
+ *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
+#define WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
+
+#include <string>
+
+#include "webrtc/api/rtpreceiverinterface.h"
+#include "webrtc/test/gmock.h"
+
+namespace webrtc {
+
+class MockRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface> {
+ public:
+  MOCK_METHOD1(SetTrack, void(MediaStreamTrackInterface*));
+  MOCK_CONST_METHOD0(track, rtc::scoped_refptr<MediaStreamTrackInterface>());
+  MOCK_CONST_METHOD0(media_type, cricket::MediaType());
+  MOCK_CONST_METHOD0(id, std::string());
+  MOCK_CONST_METHOD0(GetParameters, RtpParameters());
+  MOCK_METHOD1(SetParameters, bool(const RtpParameters&));
+  MOCK_METHOD1(SetObserver, void(RtpReceiverObserverInterface*));
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_TEST_MOCK_RTPRECEIVER_H_
diff --git a/webrtc/api/test/mock_rtpsender.h b/webrtc/api/test/mock_rtpsender.h
new file mode 100644
index 0000000..7abc4e5
--- /dev/null
+++ b/webrtc/api/test/mock_rtpsender.h
@@ -0,0 +1,36 @@
+/*
+ *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_API_TEST_MOCK_RTPSENDER_H_
+#define WEBRTC_API_TEST_MOCK_RTPSENDER_H_
+
+#include <string>
+#include <vector>
+
+#include "webrtc/api/rtpsenderinterface.h"
+#include "webrtc/test/gmock.h"
+
+namespace webrtc {
+
+class MockRtpSender : public rtc::RefCountedObject<RtpSenderInterface> {
+ public:
+  MOCK_METHOD1(SetTrack, bool(MediaStreamTrackInterface*));
+  MOCK_CONST_METHOD0(track, rtc::scoped_refptr<MediaStreamTrackInterface>());
+  MOCK_CONST_METHOD0(ssrc, uint32_t());
+  MOCK_CONST_METHOD0(media_type, cricket::MediaType());
+  MOCK_CONST_METHOD0(id, std::string());
+  MOCK_CONST_METHOD0(stream_ids, std::vector<std::string>());
+  MOCK_CONST_METHOD0(GetParameters, RtpParameters());
+  MOCK_METHOD1(SetParameters, bool(const RtpParameters&));
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_TEST_MOCK_RTPSENDER_H_
diff --git a/webrtc/api/trackmediainfomap.cc b/webrtc/api/trackmediainfomap.cc
new file mode 100644
index 0000000..0a22842
--- /dev/null
+++ b/webrtc/api/trackmediainfomap.cc
@@ -0,0 +1,201 @@
+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/api/trackmediainfomap.h"
+
+#include <utility>
+
+namespace webrtc {
+
+namespace {
+
+template<typename K, typename V>
+V FindValueOrNull(const std::map<K, V>& map, const K& key) {
+  auto it = map.find(key);
+  return (it != map.end()) ? it->second : nullptr;
+}
+
+template<typename K, typename V>
+const V* FindAddressOrNull(const std::map<K, V>& map, const K& key) {
+  auto it = map.find(key);
+  return (it != map.end()) ? &it->second : nullptr;
+}
+
+void GetAudioAndVideoTrackBySsrc(
+    const std::vector<rtc::scoped_refptr<RtpSenderInterface>>& rtp_senders,
+    const std::vector<rtc::scoped_refptr<RtpReceiverInterface>>& rtp_receivers,
+    std::map<uint32_t, AudioTrackInterface*>* audio_track_by_ssrc,
+    std::map<uint32_t, VideoTrackInterface*>* video_track_by_ssrc) {
+  RTC_DCHECK(audio_track_by_ssrc->empty());
+  RTC_DCHECK(video_track_by_ssrc->empty());
+  // TODO(hbos): RTP senders/receivers uses a proxy to the signaling thread, and
+  // our sender/receiver implementations invokes on the worker thread. (This
+  // means one thread jump if on signaling thread and two thread jumps if on any
+  // other threads). Is there a way to avoid thread jump(s) on a per
+  // sender/receiver, per method basis?
+  for (const rtc::scoped_refptr<RtpSenderInterface>& rtp_sender : rtp_senders) {
+    cricket::MediaType media_type = rtp_sender->media_type();
+    MediaStreamTrackInterface* track = rtp_sender->track();
+    if (!track) {
+      continue;
+    }
+    RTC_DCHECK_EQ(track->kind(),
+                  media_type == cricket::MEDIA_TYPE_AUDIO
+                      ? MediaStreamTrackInterface::kAudioKind
+                      : MediaStreamTrackInterface::kVideoKind);
+    // TODO(deadbeef): |ssrc| should be removed in favor of |GetParameters|.
+    uint32_t ssrc = rtp_sender->ssrc();
+    if (ssrc != 0) {
+      if (media_type == cricket::MEDIA_TYPE_AUDIO) {
+        RTC_DCHECK(audio_track_by_ssrc->find(ssrc) ==
+                   audio_track_by_ssrc->end());
+        (*audio_track_by_ssrc)[ssrc] = static_cast<AudioTrackInterface*>(track);
+      } else {
+        RTC_DCHECK(video_track_by_ssrc->find(ssrc) ==
+                   video_track_by_ssrc->end());
+        (*video_track_by_ssrc)[ssrc] = static_cast<VideoTrackInterface*>(track);
+      }
+    }
+  }
+  for (const rtc::scoped_refptr<RtpReceiverInterface>& rtp_receiver :
+       rtp_receivers) {
+    cricket::MediaType media_type = rtp_receiver->media_type();
+    MediaStreamTrackInterface* track = rtp_receiver->track();
+    RTC_DCHECK(track);
+    RTC_DCHECK_EQ(track->kind(),
+                  media_type == cricket::MEDIA_TYPE_AUDIO
+                      ? MediaStreamTrackInterface::kAudioKind
+                      : MediaStreamTrackInterface::kVideoKind);
+    RtpParameters params = rtp_receiver->GetParameters();
+    for (const RtpEncodingParameters& encoding : params.encodings) {
+      if (!encoding.ssrc) {
+        continue;
+      }
+      if (media_type == cricket::MEDIA_TYPE_AUDIO) {
+        RTC_DCHECK(audio_track_by_ssrc->find(*encoding.ssrc) ==
+                   audio_track_by_ssrc->end());
+        (*audio_track_by_ssrc)[*encoding.ssrc] =
+            static_cast<AudioTrackInterface*>(track);
+      } else {
+        RTC_DCHECK(video_track_by_ssrc->find(*encoding.ssrc) ==
+                   video_track_by_ssrc->end());
+        (*video_track_by_ssrc)[*encoding.ssrc] =
+            static_cast<VideoTrackInterface*>(track);
+      }
+    }
+  }
+}
+
+}  // namespace
+
+TrackMediaInfoMap::TrackMediaInfoMap(
+    std::unique_ptr<cricket::VoiceMediaInfo> voice_media_info,
+    std::unique_ptr<cricket::VideoMediaInfo> video_media_info,
+    const std::vector<rtc::scoped_refptr<RtpSenderInterface>>& rtp_senders,
+    const std::vector<rtc::scoped_refptr<RtpReceiverInterface>>& rtp_receivers)
+    : voice_media_info_(std::move(voice_media_info)),
+      video_media_info_(std::move(video_media_info)) {
+  std::map<uint32_t, AudioTrackInterface*> audio_track_by_ssrc;
+  std::map<uint32_t, VideoTrackInterface*> video_track_by_ssrc;
+  GetAudioAndVideoTrackBySsrc(
+      rtp_senders, rtp_receivers, &audio_track_by_ssrc, &video_track_by_ssrc);
+  if (voice_media_info_) {
+    for (auto& sender_info : voice_media_info_->senders) {
+      AudioTrackInterface* associated_track =
+          FindValueOrNull(audio_track_by_ssrc, sender_info.ssrc());
+      if (associated_track) {
+        // One sender is associated with at most one track.
+        // One track may be associated with multiple senders.
+        audio_track_by_sender_info_[&sender_info] = associated_track;
+        voice_infos_by_local_track_[associated_track].push_back(&sender_info);
+      }
+    }
+    for (auto& receiver_info : voice_media_info_->receivers) {
+      AudioTrackInterface* associated_track =
+          FindValueOrNull(audio_track_by_ssrc, receiver_info.ssrc());
+      if (associated_track) {
+        // One receiver is associated with at most one track, which is uniquely
+        // associated with that receiver.
+        audio_track_by_receiver_info_[&receiver_info] = associated_track;
+        RTC_DCHECK(voice_info_by_remote_track_.find(associated_track) ==
+                   voice_info_by_remote_track_.end());
+        voice_info_by_remote_track_[associated_track] = &receiver_info;
+      }
+    }
+  }
+  if (video_media_info_) {
+    for (auto& sender_info : video_media_info_->senders) {
+      VideoTrackInterface* associated_track =
+          FindValueOrNull(video_track_by_ssrc, sender_info.ssrc());
+      if (associated_track) {
+        // One sender is associated with at most one track.
+        // One track may be associated with multiple senders.
+        video_track_by_sender_info_[&sender_info] = associated_track;
+        video_infos_by_local_track_[associated_track].push_back(&sender_info);
+      }
+    }
+    for (auto& receiver_info : video_media_info_->receivers) {
+      VideoTrackInterface* associated_track =
+          FindValueOrNull(video_track_by_ssrc, receiver_info.ssrc());
+      if (associated_track) {
+        // One receiver is associated with at most one track, which is uniquely
+        // associated with that receiver.
+        video_track_by_receiver_info_[&receiver_info] = associated_track;
+        RTC_DCHECK(video_info_by_remote_track_.find(associated_track) ==
+                   video_info_by_remote_track_.end());
+        video_info_by_remote_track_[associated_track] = &receiver_info;
+      }
+    }
+  }
+}
+
+const std::vector<cricket::VoiceSenderInfo*>*
+TrackMediaInfoMap::GetVoiceSenderInfos(
+    const AudioTrackInterface& local_audio_track) const {
+  return FindAddressOrNull(voice_infos_by_local_track_, &local_audio_track);
+}
+
+const cricket::VoiceReceiverInfo* TrackMediaInfoMap::GetVoiceReceiverInfo(
+    const AudioTrackInterface& remote_audio_track) const {
+  return FindValueOrNull(voice_info_by_remote_track_, &remote_audio_track);
+}
+
+const std::vector<cricket::VideoSenderInfo*>*
+TrackMediaInfoMap::GetVideoSenderInfos(
+    const VideoTrackInterface& local_video_track) const {
+  return FindAddressOrNull(video_infos_by_local_track_, &local_video_track);
+}
+
+const cricket::VideoReceiverInfo* TrackMediaInfoMap::GetVideoReceiverInfo(
+    const VideoTrackInterface& remote_video_track) const {
+  return FindValueOrNull(video_info_by_remote_track_, &remote_video_track);
+}
+
+rtc::scoped_refptr<AudioTrackInterface> TrackMediaInfoMap::GetAudioTrack(
+    const cricket::VoiceSenderInfo& voice_sender_info) const {
+  return FindValueOrNull(audio_track_by_sender_info_, &voice_sender_info);
+}
+
+rtc::scoped_refptr<AudioTrackInterface> TrackMediaInfoMap::GetAudioTrack(
+    const cricket::VoiceReceiverInfo& voice_receiver_info) const {
+  return FindValueOrNull(audio_track_by_receiver_info_, &voice_receiver_info);
+}
+
+rtc::scoped_refptr<VideoTrackInterface> TrackMediaInfoMap::GetVideoTrack(
+    const cricket::VideoSenderInfo& video_sender_info) const {
+  return FindValueOrNull(video_track_by_sender_info_, &video_sender_info);
+}
+
+rtc::scoped_refptr<VideoTrackInterface> TrackMediaInfoMap::GetVideoTrack(
+    const cricket::VideoReceiverInfo& video_receiver_info) const {
+  return FindValueOrNull(video_track_by_receiver_info_, &video_receiver_info);
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/trackmediainfomap.h b/webrtc/api/trackmediainfomap.h
new file mode 100644
index 0000000..7bf0977
--- /dev/null
+++ b/webrtc/api/trackmediainfomap.h
@@ -0,0 +1,98 @@
+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_API_TRACKMEDIAINFOMAP_H_
+#define WEBRTC_API_TRACKMEDIAINFOMAP_H_
+
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "webrtc/api/mediastreaminterface.h"
+#include "webrtc/api/rtpreceiverinterface.h"
+#include "webrtc/api/rtpsenderinterface.h"
+#include "webrtc/base/refcount.h"
+#include "webrtc/media/base/mediachannel.h"
+
+namespace webrtc {
+
+// Audio/video tracks and sender/receiver statistical information are associated
+// with each other based on attachments to RTP senders/receivers. This class
+// maps that relationship, in both directions, so that stats about a track can
+// be retrieved on a per-attachment basis.
+//
+// An RTP sender/receiver sends or receives media for a set of SSRCs. The media
+// comes from an audio/video track that is attached to it.
+// |[Voice/Video][Sender/Receiver]Info| has statistical information for a set of
+// SSRCs. Looking at the RTP senders and receivers uncovers the track <-> info
+// relationships, which this class does.
+class TrackMediaInfoMap {
+ public:
+  TrackMediaInfoMap(
+      std::unique_ptr<cricket::VoiceMediaInfo> voice_media_info,
+      std::unique_ptr<cricket::VideoMediaInfo> video_media_info,
+      const std::vector<rtc::scoped_refptr<RtpSenderInterface>>& rtp_senders,
+      const std::vector<rtc::scoped_refptr<RtpReceiverInterface>>&
+          rtp_receivers);
+
+  const cricket::VoiceMediaInfo* voice_media_info() const {
+    return voice_media_info_.get();
+  }
+  const cricket::VideoMediaInfo* video_media_info() const {
+    return video_media_info_.get();
+  }
+
+  const std::vector<cricket::VoiceSenderInfo*>* GetVoiceSenderInfos(
+      const AudioTrackInterface& local_audio_track) const;
+  const cricket::VoiceReceiverInfo* GetVoiceReceiverInfo(
+      const AudioTrackInterface& remote_audio_track) const;
+  const std::vector<cricket::VideoSenderInfo*>* GetVideoSenderInfos(
+      const VideoTrackInterface& local_video_track) const;
+  const cricket::VideoReceiverInfo* GetVideoReceiverInfo(
+      const VideoTrackInterface& remote_video_track) const;
+
+  rtc::scoped_refptr<AudioTrackInterface> GetAudioTrack(
+      const cricket::VoiceSenderInfo& voice_sender_info) const;
+  rtc::scoped_refptr<AudioTrackInterface> GetAudioTrack(
+      const cricket::VoiceReceiverInfo& voice_receiver_info) const;
+  rtc::scoped_refptr<VideoTrackInterface> GetVideoTrack(
+      const cricket::VideoSenderInfo& video_sender_info) const;
+  rtc::scoped_refptr<VideoTrackInterface> GetVideoTrack(
+      const cricket::VideoReceiverInfo& video_receiver_info) const;
+
+ private:
+  std::unique_ptr<cricket::VoiceMediaInfo> voice_media_info_;
+  std::unique_ptr<cricket::VideoMediaInfo> video_media_info_;
+  // These maps map tracks (identified by a pointer) to their corresponding info
+  // object of the correct kind. One track can map to multiple info objects.
+  std::map<const AudioTrackInterface*, std::vector<cricket::VoiceSenderInfo*>>
+      voice_infos_by_local_track_;
+  std::map<const AudioTrackInterface*, cricket::VoiceReceiverInfo*>
+      voice_info_by_remote_track_;
+  std::map<const VideoTrackInterface*, std::vector<cricket::VideoSenderInfo*>>
+      video_infos_by_local_track_;
+  std::map<const VideoTrackInterface*, cricket::VideoReceiverInfo*>
+      video_info_by_remote_track_;
+  // These maps map info objects to their corresponding tracks. They are always
+  // the inverse of the maps above. One info object always maps to only one
+  // track.
+  std::map<const cricket::VoiceSenderInfo*,
+      rtc::scoped_refptr<AudioTrackInterface>> audio_track_by_sender_info_;
+  std::map<const cricket::VoiceReceiverInfo*,
+      rtc::scoped_refptr<AudioTrackInterface>> audio_track_by_receiver_info_;
+  std::map<const cricket::VideoSenderInfo*,
+      rtc::scoped_refptr<VideoTrackInterface>> video_track_by_sender_info_;
+  std::map<const cricket::VideoReceiverInfo*,
+      rtc::scoped_refptr<VideoTrackInterface>> video_track_by_receiver_info_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_TRACKMEDIAINFOMAP_H_
diff --git a/webrtc/api/trackmediainfomap_unittest.cc b/webrtc/api/trackmediainfomap_unittest.cc
new file mode 100644
index 0000000..a8ff6c2
--- /dev/null
+++ b/webrtc/api/trackmediainfomap_unittest.cc
@@ -0,0 +1,381 @@
+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/api/trackmediainfomap.h"
+
+#include <initializer_list>
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "webrtc/api/audiotrack.h"
+#include "webrtc/api/rtpreceiverinterface.h"
+#include "webrtc/api/rtpsenderinterface.h"
+#include "webrtc/api/test/mock_rtpreceiver.h"
+#include "webrtc/api/test/mock_rtpsender.h"
+#include "webrtc/api/test/fakevideotracksource.h"
+#include "webrtc/api/videotrack.h"
+#include "webrtc/base/refcount.h"
+#include "webrtc/media/base/mediachannel.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+namespace {
+
+RtpParameters CreateRtpParametersWithSsrcs(
+    std::initializer_list<uint32_t> ssrcs) {
+  RtpParameters params;
+  for (uint32_t ssrc : ssrcs) {
+    RtpEncodingParameters encoding_params;
+    encoding_params.ssrc = rtc::Optional<uint32_t>(ssrc);
+    params.encodings.push_back(encoding_params);
+  }
+  return params;
+}
+
+rtc::scoped_refptr<MockRtpSender> CreateMockRtpSender(
+    cricket::MediaType media_type, std::initializer_list<uint32_t> ssrcs,
+    rtc::scoped_refptr<MediaStreamTrackInterface> track) {
+  uint32_t first_ssrc;
+  if (ssrcs.size()) {
+    first_ssrc = *ssrcs.begin();
+  } else {
+    first_ssrc = 0;
+  }
+  rtc::scoped_refptr<MockRtpSender> sender(
+      new rtc::RefCountedObject<MockRtpSender>());
+  EXPECT_CALL(*sender, track()).WillRepeatedly(testing::Return(track));
+  EXPECT_CALL(*sender, ssrc()).WillRepeatedly(testing::Return(first_ssrc));
+  EXPECT_CALL(*sender, media_type()).WillRepeatedly(testing::Return(
+      media_type));
+  EXPECT_CALL(*sender, GetParameters()).WillRepeatedly(testing::Return(
+      CreateRtpParametersWithSsrcs(ssrcs)));
+  return sender;
+}
+
+rtc::scoped_refptr<MockRtpReceiver> CreateMockRtpReceiver(
+    cricket::MediaType media_type, std::initializer_list<uint32_t> ssrcs,
+    rtc::scoped_refptr<MediaStreamTrackInterface> track) {
+  rtc::scoped_refptr<MockRtpReceiver> receiver(
+      new rtc::RefCountedObject<MockRtpReceiver>());
+  EXPECT_CALL(*receiver, track()).WillRepeatedly(testing::Return(track));
+  EXPECT_CALL(*receiver, media_type()).WillRepeatedly(testing::Return(
+      media_type));
+  EXPECT_CALL(*receiver, GetParameters()).WillRepeatedly(testing::Return(
+      CreateRtpParametersWithSsrcs(ssrcs)));
+  return receiver;
+}
+
+class TrackMediaInfoMapTest : public testing::Test {
+ public:
+  TrackMediaInfoMapTest()
+      : voice_media_info_(new cricket::VoiceMediaInfo()),
+        video_media_info_(new cricket::VideoMediaInfo()),
+        local_audio_track_(AudioTrack::Create("LocalAudioTrack", nullptr)),
+        remote_audio_track_(AudioTrack::Create("RemoteAudioTrack", nullptr)),
+        local_video_track_(
+            VideoTrack::Create("LocalVideoTrack",
+                               FakeVideoTrackSource::Create(false))),
+        remote_video_track_(
+            VideoTrack::Create("RemoteVideoTrack",
+                               FakeVideoTrackSource::Create(false))) {
+  }
+
+  ~TrackMediaInfoMapTest() {
+    // If we have a map the ownership has been passed to the map, only delete if
+    // |CreateMap| has not been called.
+    if (!map_) {
+      delete voice_media_info_;
+      delete video_media_info_;
+    }
+  }
+
+  void AddRtpSenderWithSsrcs(std::initializer_list<uint32_t> ssrcs,
+                             MediaStreamTrackInterface* local_track) {
+    rtc::scoped_refptr<MockRtpSender> rtp_sender = CreateMockRtpSender(
+        local_track->kind() == MediaStreamTrackInterface::kAudioKind ?
+            cricket::MEDIA_TYPE_AUDIO : cricket::MEDIA_TYPE_VIDEO,
+        ssrcs, local_track);
+    rtp_senders_.push_back(rtp_sender);
+
+    if (local_track->kind() == MediaStreamTrackInterface::kAudioKind) {
+      cricket::VoiceSenderInfo voice_sender_info;
+      size_t i = 0;
+      for (uint32_t ssrc : ssrcs) {
+        voice_sender_info.local_stats.push_back(cricket::SsrcSenderInfo());
+        voice_sender_info.local_stats[i++].ssrc = ssrc;
+      }
+      voice_media_info_->senders.push_back(voice_sender_info);
+    } else {
+      cricket::VideoSenderInfo video_sender_info;
+      size_t i = 0;
+      for (uint32_t ssrc : ssrcs) {
+        video_sender_info.local_stats.push_back(cricket::SsrcSenderInfo());
+        video_sender_info.local_stats[i++].ssrc = ssrc;
+      }
+      video_media_info_->senders.push_back(video_sender_info);
+    }
+  }
+
+  void AddRtpReceiverWithSsrcs(std::initializer_list<uint32_t> ssrcs,
+                               MediaStreamTrackInterface* remote_track) {
+    rtc::scoped_refptr<MockRtpReceiver> rtp_receiver = CreateMockRtpReceiver(
+        remote_track->kind() == MediaStreamTrackInterface::kAudioKind ?
+            cricket::MEDIA_TYPE_AUDIO : cricket::MEDIA_TYPE_VIDEO,
+        ssrcs, remote_track);
+    rtp_receivers_.push_back(rtp_receiver);
+
+    if (remote_track->kind() == MediaStreamTrackInterface::kAudioKind) {
+      cricket::VoiceReceiverInfo voice_receiver_info;
+      size_t i = 0;
+      for (uint32_t ssrc : ssrcs) {
+        voice_receiver_info.local_stats.push_back(cricket::SsrcReceiverInfo());
+        voice_receiver_info.local_stats[i++].ssrc = ssrc;
+      }
+      voice_media_info_->receivers.push_back(voice_receiver_info);
+    } else {
+      cricket::VideoReceiverInfo video_receiver_info;
+      size_t i = 0;
+      for (uint32_t ssrc : ssrcs) {
+        video_receiver_info.local_stats.push_back(cricket::SsrcReceiverInfo());
+        video_receiver_info.local_stats[i++].ssrc = ssrc;
+      }
+      video_media_info_->receivers.push_back(video_receiver_info);
+    }
+  }
+
+  void CreateMap() {
+    RTC_DCHECK(!map_);
+    map_.reset(new TrackMediaInfoMap(
+        std::unique_ptr<cricket::VoiceMediaInfo>(voice_media_info_),
+        std::unique_ptr<cricket::VideoMediaInfo>(video_media_info_),
+        rtp_senders_,
+        rtp_receivers_));
+  }
+
+ protected:
+  cricket::VoiceMediaInfo* voice_media_info_;
+  cricket::VideoMediaInfo* video_media_info_;
+  std::vector<rtc::scoped_refptr<RtpSenderInterface>> rtp_senders_;
+  std::vector<rtc::scoped_refptr<RtpReceiverInterface>> rtp_receivers_;
+  std::unique_ptr<TrackMediaInfoMap> map_;
+  rtc::scoped_refptr<AudioTrack> local_audio_track_;
+  rtc::scoped_refptr<AudioTrack> remote_audio_track_;
+  rtc::scoped_refptr<VideoTrack> local_video_track_;
+  rtc::scoped_refptr<VideoTrack> remote_video_track_;
+};
+
+}  // namespace
+
+TEST_F(TrackMediaInfoMapTest, SingleSenderReceiverPerTrackWithOneSsrc) {
+  AddRtpSenderWithSsrcs({ 1 }, local_audio_track_);
+  AddRtpReceiverWithSsrcs({ 2 }, remote_audio_track_);
+  AddRtpSenderWithSsrcs({ 3 }, local_video_track_);
+  AddRtpReceiverWithSsrcs({ 4 }, remote_video_track_);
+  CreateMap();
+
+  // Local audio track <-> RTP audio sender
+  ASSERT_TRUE(map_->GetVoiceSenderInfos(*local_audio_track_));
+  EXPECT_EQ(*map_->GetVoiceSenderInfos(*local_audio_track_),
+            std::vector<cricket::VoiceSenderInfo*>({
+                &voice_media_info_->senders[0] }));
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[0]),
+            local_audio_track_.get());
+
+  // Remote audio track <-> RTP audio receiver
+  EXPECT_EQ(map_->GetVoiceReceiverInfo(*remote_audio_track_),
+            &voice_media_info_->receivers[0]);
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->receivers[0]),
+            remote_audio_track_.get());
+
+  // Local video track <-> RTP video sender
+  ASSERT_TRUE(map_->GetVideoSenderInfos(*local_video_track_));
+  EXPECT_EQ(*map_->GetVideoSenderInfos(*local_video_track_),
+            std::vector<cricket::VideoSenderInfo*>({
+                &video_media_info_->senders[0] }));
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[0]),
+            local_video_track_.get());
+
+  // Remote video track <-> RTP video receiver
+  EXPECT_EQ(map_->GetVideoReceiverInfo(*remote_video_track_),
+            &video_media_info_->receivers[0]);
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->receivers[0]),
+            remote_video_track_.get());
+}
+
+TEST_F(TrackMediaInfoMapTest, SingleSenderReceiverPerTrackWithMissingSsrc) {
+  AddRtpSenderWithSsrcs({}, local_audio_track_);
+  AddRtpSenderWithSsrcs({}, local_video_track_);
+  AddRtpReceiverWithSsrcs({}, remote_audio_track_);
+  AddRtpReceiverWithSsrcs({}, remote_video_track_);
+  CreateMap();
+
+  EXPECT_FALSE(map_->GetVoiceSenderInfos(*local_audio_track_));
+  EXPECT_FALSE(map_->GetVideoSenderInfos(*local_video_track_));
+  EXPECT_FALSE(map_->GetVoiceReceiverInfo(*remote_audio_track_));
+  EXPECT_FALSE(map_->GetVideoReceiverInfo(*remote_video_track_));
+}
+
+TEST_F(TrackMediaInfoMapTest,
+       SingleSenderReceiverPerTrackWithAudioAndVideoUseSameSsrc) {
+  AddRtpSenderWithSsrcs({ 1 }, local_audio_track_);
+  AddRtpReceiverWithSsrcs({ 2 }, remote_audio_track_);
+  AddRtpSenderWithSsrcs({ 1 }, local_video_track_);
+  AddRtpReceiverWithSsrcs({ 2 }, remote_video_track_);
+  CreateMap();
+
+  // Local audio track <-> RTP audio sender
+  ASSERT_TRUE(map_->GetVoiceSenderInfos(*local_audio_track_));
+  EXPECT_EQ(*map_->GetVoiceSenderInfos(*local_audio_track_),
+            std::vector<cricket::VoiceSenderInfo*>({
+                &voice_media_info_->senders[0] }));
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[0]),
+            local_audio_track_.get());
+
+  // Remote audio track <-> RTP audio receiver
+  EXPECT_EQ(map_->GetVoiceReceiverInfo(*remote_audio_track_),
+            &voice_media_info_->receivers[0]);
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->receivers[0]),
+            remote_audio_track_.get());
+
+  // Local video track <-> RTP video sender
+  ASSERT_TRUE(map_->GetVideoSenderInfos(*local_video_track_));
+  EXPECT_EQ(*map_->GetVideoSenderInfos(*local_video_track_),
+            std::vector<cricket::VideoSenderInfo*>({
+                &video_media_info_->senders[0] }));
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[0]),
+            local_video_track_.get());
+
+  // Remote video track <-> RTP video receiver
+  EXPECT_EQ(map_->GetVideoReceiverInfo(*remote_video_track_),
+            &video_media_info_->receivers[0]);
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->receivers[0]),
+            remote_video_track_.get());
+}
+
+TEST_F(TrackMediaInfoMapTest, SingleMultiSsrcSenderPerTrack) {
+  AddRtpSenderWithSsrcs({ 1, 2 }, local_audio_track_);
+  AddRtpSenderWithSsrcs({ 3, 4 }, local_video_track_);
+  CreateMap();
+
+  // Local audio track <-> RTP audio senders
+  ASSERT_TRUE(map_->GetVoiceSenderInfos(*local_audio_track_));
+  EXPECT_EQ(*map_->GetVoiceSenderInfos(*local_audio_track_),
+            std::vector<cricket::VoiceSenderInfo*>({
+                &voice_media_info_->senders[0] }));
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[0]),
+            local_audio_track_.get());
+
+  // Local video track <-> RTP video senders
+  ASSERT_TRUE(map_->GetVideoSenderInfos(*local_video_track_));
+  EXPECT_EQ(*map_->GetVideoSenderInfos(*local_video_track_),
+            std::vector<cricket::VideoSenderInfo*>({
+                &video_media_info_->senders[0] }));
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[0]),
+            local_video_track_.get());
+}
+
+TEST_F(TrackMediaInfoMapTest, MultipleOneSsrcSendersPerTrack) {
+  AddRtpSenderWithSsrcs({ 1 }, local_audio_track_);
+  AddRtpSenderWithSsrcs({ 2 }, local_audio_track_);
+  AddRtpSenderWithSsrcs({ 3 }, local_video_track_);
+  AddRtpSenderWithSsrcs({ 4 }, local_video_track_);
+  CreateMap();
+
+  // Local audio track <-> RTP audio senders
+  ASSERT_TRUE(map_->GetVoiceSenderInfos(*local_audio_track_));
+  EXPECT_EQ(*map_->GetVoiceSenderInfos(*local_audio_track_),
+            std::vector<cricket::VoiceSenderInfo*>({
+                &voice_media_info_->senders[0],
+                &voice_media_info_->senders[1] }));
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[0]),
+            local_audio_track_.get());
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[1]),
+            local_audio_track_.get());
+
+  // Local video track <-> RTP video senders
+  ASSERT_TRUE(map_->GetVideoSenderInfos(*local_video_track_));
+  EXPECT_EQ(*map_->GetVideoSenderInfos(*local_video_track_),
+            std::vector<cricket::VideoSenderInfo*>({
+                &video_media_info_->senders[0],
+                &video_media_info_->senders[1] }));
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[0]),
+            local_video_track_.get());
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[1]),
+            local_video_track_.get());
+}
+
+TEST_F(TrackMediaInfoMapTest, MultipleMultiSsrcSendersPerTrack) {
+  AddRtpSenderWithSsrcs({ 1, 2 }, local_audio_track_);
+  AddRtpSenderWithSsrcs({ 3, 4 }, local_audio_track_);
+  AddRtpSenderWithSsrcs({ 5, 6 }, local_video_track_);
+  AddRtpSenderWithSsrcs({ 7, 8 }, local_video_track_);
+  CreateMap();
+
+  // Local audio track <-> RTP audio senders
+  ASSERT_TRUE(map_->GetVoiceSenderInfos(*local_audio_track_));
+  EXPECT_EQ(*map_->GetVoiceSenderInfos(*local_audio_track_),
+            std::vector<cricket::VoiceSenderInfo*>({
+                &voice_media_info_->senders[0],
+                &voice_media_info_->senders[1] }));
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[0]),
+            local_audio_track_.get());
+  EXPECT_EQ(map_->GetAudioTrack(voice_media_info_->senders[1]),
+            local_audio_track_.get());
+
+  // Local video track <-> RTP video senders
+  ASSERT_TRUE(map_->GetVideoSenderInfos(*local_video_track_));
+  EXPECT_EQ(*map_->GetVideoSenderInfos(*local_video_track_),
+            std::vector<cricket::VideoSenderInfo*>({
+                &video_media_info_->senders[0],
+                &video_media_info_->senders[1] }));
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[0]),
+            local_video_track_.get());
+  EXPECT_EQ(map_->GetVideoTrack(video_media_info_->senders[1]),
+            local_video_track_.get());
+}
+
+// Death tests.
+// Disabled on Android because death tests misbehave on Android, see
+// base/test/gtest_util.h.
+#if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+
+class TrackMediaInfoMapDeathTest : public TrackMediaInfoMapTest {
+};
+
+TEST_F(TrackMediaInfoMapDeathTest, MultipleOneSsrcReceiversPerTrack) {
+  AddRtpReceiverWithSsrcs({ 1 }, remote_audio_track_);
+  AddRtpReceiverWithSsrcs({ 2 }, remote_audio_track_);
+  AddRtpReceiverWithSsrcs({ 3 }, remote_video_track_);
+  AddRtpReceiverWithSsrcs({ 4 }, remote_video_track_);
+  EXPECT_DEATH(CreateMap(), "");
+}
+
+TEST_F(TrackMediaInfoMapDeathTest, MultipleMultiSsrcReceiversPerTrack) {
+  AddRtpReceiverWithSsrcs({ 1, 2 }, remote_audio_track_);
+  AddRtpReceiverWithSsrcs({ 3, 4 }, remote_audio_track_);
+  AddRtpReceiverWithSsrcs({ 5, 6 }, remote_video_track_);
+  AddRtpReceiverWithSsrcs({ 7, 8 }, remote_video_track_);
+  EXPECT_DEATH(CreateMap(), "");
+}
+
+TEST_F(TrackMediaInfoMapDeathTest,
+       SingleSenderReceiverPerTrackWithSsrcNotUnique) {
+  AddRtpSenderWithSsrcs({ 1 }, local_audio_track_);
+  AddRtpReceiverWithSsrcs({ 1 }, remote_audio_track_);
+  AddRtpSenderWithSsrcs({ 2 }, local_video_track_);
+  AddRtpReceiverWithSsrcs({ 2 }, remote_video_track_);
+  EXPECT_DEATH(CreateMap(), "");
+}
+
+#endif  // RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+
+}  // namespace webrtc