Interface RTCRtpReceiver and RTCPeerConnection.getReceivers() added.

content/renderer/media/rtc_peer_connection_handler.cc

Index: content/renderer/media/rtc_peer_connection_handler.cc
diff --git a/content/renderer/media/rtc_peer_connection_handler.cc b/content/renderer/media/rtc_peer_connection_handler.cc
index 3240a7a2fbe2e9e97bb3f0bade3ce22d159fb618..526ef51516487d1150893c5f6df20a0a5dd2d089 100644
--- a/content/renderer/media/rtc_peer_connection_handler.cc
+++ b/content/renderer/media/rtc_peer_connection_handler.cc
@@ -29,6 +29,7 @@
 #include "content/renderer/media/rtc_data_channel_handler.h"
 #include "content/renderer/media/rtc_dtmf_sender_handler.h"
 #include "content/renderer/media/webrtc/peer_connection_dependency_factory.h"
+#include "content/renderer/media/webrtc/rtc_rtp_receiver.h"
 #include "content/renderer/media/webrtc/rtc_stats.h"
 #include "content/renderer/media/webrtc/webrtc_media_stream_adapter.h"
 #include "content/renderer/media/webrtc_audio_device_impl.h"
@@ -1634,6 +1635,46 @@ void RTCPeerConnectionHandler::getStats(
           base::Passed(&callback)));
 }
 
+blink::WebVector<std::unique_ptr<blink::WebRTCRtpReceiver>>
+RTCPeerConnectionHandler::getReceivers() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  TRACE_EVENT0("webrtc", "RTCPeerConnectionHandler::getReceivers");
+
+  std::vector<rtc::scoped_refptr<webrtc::RtpReceiverInterface>>
+      webrtc_receivers = native_peer_connection_->GetReceivers();
+  std::vector<std::unique_ptr<blink::WebRTCRtpReceiver>> web_receivers;
+  for (size_t i = 0; i < webrtc_receivers.size(); ++i) {
+    rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> webrtc_track =
+        webrtc_receivers[i]->track();
+    DCHECK(webrtc_track);
+    // Create a reference to the receiver. Multiple |RTCRtpReceiver|s can
+    // reference the same webrtc track, see |id|.
+    blink::WebMediaStreamTrack web_track;
+    if (webrtc_track->kind() == webrtc::MediaStreamTrackInterface::kAudioKind) {
+      web_track = GetRemoteAudioTrack(webrtc_track->id());
+    } else {
+      web_track = GetRemoteVideoTrack(webrtc_track->id());
+    }
+    // TODO(hbos): Any existing remote track should be known but the case of a
+    // track being added or removed separately from streams is not handled
+    // properly, see todo in |GetRemoteAudioTrack| and |GetRemoteVideoTrack|.
+    // When that is addressed, DCHECK that the track is not null.

[Guido Urdaneta, 2017/03/27 17:12:23]

reference crbug

[hbos_chromium, 2017/03/28 10:12:55]

Done.

+    if (!web_track.isNull()) {
+      web_receivers.push_back(std::unique_ptr<blink::WebRTCRtpReceiver>(

[Guido Urdaneta, 2017/03/27 17:12:23]

use emplace_back or base::MakeUnique instead of unique_ptr<>(new...)

[hbos_chromium, 2017/03/28 10:12:55]

Done.

[Guido Urdaneta, 2017/03/28 14:27:03]

Nit: I know I suggested emplace_back, but I overlooked that you were storing
pointers. 
Now I think MakeUnique with push_back aligns better with the style guide.
I believe the recommendation nowadays is to avoid new and delete in new code if
you can.

[hbos_chromium, 2017/03/29 14:36:42]

Done.

+          new RTCRtpReceiver(webrtc_receivers[i].get(), web_track)));
+    }
+  }
+
+  // |blink::WebVector|'s size must be known at construction, that is why
+  // |web_vectors| uses |std::vector| and needs to be moved before returning.
+  blink::WebVector<std::unique_ptr<blink::WebRTCRtpReceiver>> result(
+      web_receivers.size());
+  for (size_t i = 0; i < web_receivers.size(); ++i) {
+    result[i] = std::move(web_receivers[i]);
+  }
+  return result;
+}
+
 void RTCPeerConnectionHandler::CloseClientPeerConnection() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!is_closed_)
@@ -1994,6 +2035,40 @@ void RTCPeerConnectionHandler::RunSynchronousClosureOnSignalingThread(
   }
 }
 
+blink::WebMediaStreamTrack RTCPeerConnectionHandler::GetRemoteAudioTrack(
+    const std::string& track_id) const {

[Guido Urdaneta, 2017/03/27 17:12:23]

Since both methods are the same except for getAudioTrack/getVideoTrack, maybe
you can have a third method that does the logic and receives a pointer to the
method to use.

[hbos_chromium, 2017/03/28 10:12:54]

Done.

+  // TODO(hbos): Tracks and streams are currently added/removed on a per-stream
+  // basis, but tracks could be removed from a stream or added to an existing
+  // stream. We need to listen to events of tracks being added and removed, and
+  // have a list of tracks that is separate from the list of streams.
+  DCHECK(thread_checker_.CalledOnValidThread());
+  blink::WebString id = blink::WebString::fromUTF8(track_id);
+  for (const auto& remote_stream_pair : remote_streams_) {
+    blink::WebMediaStreamTrack web_track =
+        remote_stream_pair.second->webkit_stream().getAudioTrack(id);
+    if (!web_track.isNull())
+      return web_track;
+  }
+  return blink::WebMediaStreamTrack();
+}
+
+blink::WebMediaStreamTrack RTCPeerConnectionHandler::GetRemoteVideoTrack(
+    const std::string& track_id) const {
+  // TODO(hbos): Tracks and streams are currently added/removed on a per-stream
+  // basis, but tracks could be removed from a stream or added to an existing
+  // stream. We need to listen to events of tracks being added and removed, and
+  // have a list of tracks that is separate from the list of streams.
+  DCHECK(thread_checker_.CalledOnValidThread());
+  blink::WebString id = blink::WebString::fromUTF8(track_id);
+  for (const auto& remote_stream_pair : remote_streams_) {
+    blink::WebMediaStreamTrack web_track =
+        remote_stream_pair.second->webkit_stream().getVideoTrack(id);
+    if (!web_track.isNull())
+      return web_track;
+  }
+  return blink::WebMediaStreamTrack();
+}
+
 void RTCPeerConnectionHandler::ReportICEState(
     webrtc::PeerConnectionInterface::IceConnectionState new_state) {
   DCHECK(thread_checker_.CalledOnValidThread());