content::RTCRtpSenders/Receivers using track adapter references.

content/renderer/media/webrtc/rtc_rtp_receiver.h

 // Copyright (c) 2017 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_RENDERER_MEDIA_WEBRTC_RTC_RTP_RECEIVER_H_
 #define CONTENT_RENDERER_MEDIA_WEBRTC_RTC_RTP_RECEIVER_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "content/common/content_export.h"
+#include "content/renderer/media/webrtc/webrtc_media_stream_track_adapter_map.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
 #include "third_party/WebKit/public/platform/WebRTCRtpReceiver.h"
 #include "third_party/webrtc/api/rtpreceiverinterface.h"
 
 namespace content {
 
 // Used to surface |webrtc::RtpReceiverInterface| to blink. Multiple
 // |RTCRtpReceiver|s could reference the same webrtc receiver; |id| is the value
 // of the pointer to the webrtc receiver.
 class CONTENT_EXPORT RTCRtpReceiver : public blink::WebRTCRtpReceiver {
  public:
   static uintptr_t getId(
       const webrtc::RtpReceiverInterface* webrtc_rtp_receiver);
 
   RTCRtpReceiver(webrtc::RtpReceiverInterface* webrtc_rtp_receiver,

[Guido Urdaneta, 2017/06/19 16:10:51]

Update raw pointer to scoped_refptr by value.

According to
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/TlL1D-Djt...

the consensus on passing scoped_refptr to a function that takes ownership is to
pass it by value and then call std::move() internally to avoid the additional
AddRef.

[hbos_chromium, 2017/06/19 16:45:39]

I've never seen std::move be used in combination with scoped_refptr in our
codebase, and I think moving can be misleading since ownership is still shared,
but I've seen const scoped_refptr<>& all over the place. I'll do that?

[Guido Urdaneta, 2017/06/20 11:26:15]

Pass by value, not const-ref

-                 const blink::WebMediaStreamTrack& web_track);
+                 std::unique_ptr<WebRtcMediaStreamTrackAdapterMap::AdapterRef>
+                     track_adapter);
   ~RTCRtpReceiver() override;
 
   uintptr_t Id() const override;
   const blink::WebMediaStreamTrack& Track() const override;
   blink::WebVector<std::unique_ptr<blink::WebRTCRtpContributingSource>>
   GetSources() override;
 
   const webrtc::MediaStreamTrackInterface& webrtc_track() const;
 
  private:
   const scoped_refptr<webrtc::RtpReceiverInterface> webrtc_rtp_receiver_;
-  const blink::WebMediaStreamTrack web_track_;
+  // The track adapter is the glue between blink and webrtc layer tracks.
+  // Keeping a reference to the adapter ensures it is not disposed, as is
+  // required as long as the webrtc layer track is in use by the receiver.
+  std::unique_ptr<WebRtcMediaStreamTrackAdapterMap::AdapterRef> track_adapter_;
 
   DISALLOW_COPY_AND_ASSIGN(RTCRtpReceiver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_WEBRTC_RTC_RTP_RECEIVER_H_