RTCRtpSender with track behind RuntimeEnabled flag

content/renderer/media/webrtc/rtc_rtp_sender.cc

Index: content/renderer/media/webrtc/rtc_rtp_sender.cc
diff --git a/content/renderer/media/webrtc/rtc_rtp_sender.cc b/content/renderer/media/webrtc/rtc_rtp_sender.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2d61389b39d2a4c00c9739471dbfdd884682f0b3
--- /dev/null
+++ b/content/renderer/media/webrtc/rtc_rtp_sender.cc
@@ -0,0 +1,52 @@
+// 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.
+
+#include "content/renderer/media/webrtc/rtc_rtp_sender.h"
+
+#include "base/logging.h"
+#include "third_party/webrtc/base/scoped_ref_ptr.h"
+
+namespace content {
+
+namespace {
+
+inline bool operator==(
+    const std::unique_ptr<blink::WebMediaStreamTrack>& web_track,
+    const webrtc::MediaStreamTrackInterface* webrtc_track) {
+  if (!web_track)
+    return !webrtc_track;
+  return webrtc_track && web_track->Id() == webrtc_track->id().c_str();
+}
+
+}  // namespace
+
+uintptr_t RTCRtpSender::getId(
+    const webrtc::RtpSenderInterface* webrtc_rtp_sender) {
+  return reinterpret_cast<uintptr_t>(webrtc_rtp_sender);

[Guido Urdaneta, 2017/05/02 12:31:48]

Does this always work? Is there another way to get an ID?

[hbos_chromium, 2017/05/03 09:54:23]

The only requirement of IDs is that they're a way of uniquely identifying an
existing sender, this achieves that without needing additional logic.

If a sender is deleted then theoretically another sender could be created in the
future reusing the same ID (position in memory) but this does not cause any
problems. The map is for the ID -> blink sender map, and as long as a blink
sender is kept-alive so is the webrtc sender, there are never any possible
conflicts.

I prefer this for simplicity and it's how receivers is implemented. I added a
comment in the interface clarifying that IDs may be reused.

+}
+
+RTCRtpSender::RTCRtpSender(
+    webrtc::RtpSenderInterface* webrtc_rtp_sender,
+    std::unique_ptr<blink::WebMediaStreamTrack> web_track)
+    : webrtc_rtp_sender_(webrtc_rtp_sender), web_track_(std::move(web_track)) {
+  DCHECK(webrtc_rtp_sender_);
+  DCHECK(web_track_ == webrtc_track());
+}
+
+RTCRtpSender::~RTCRtpSender() {}
+
+uintptr_t RTCRtpSender::Id() const {
+  return getId(webrtc_rtp_sender_.get());
+}
+
+const blink::WebMediaStreamTrack* RTCRtpSender::Track() const {
+  DCHECK(web_track_ == webrtc_track());

[Guido Urdaneta, 2017/05/02 12:31:48]

Does DCHECK_EQ work in this case?

[hbos_chromium, 2017/05/03 09:54:23]

No, not without defining more functions. Last I tried it got messy.

+  return web_track_.get();
+}
+
+const webrtc::MediaStreamTrackInterface* RTCRtpSender::webrtc_track() const {
+  return webrtc_rtp_sender_->track();
+}
+
+}  // namespace content