Introduce RtpStreamReceiver and RtpStreamReceiverControllerInterface.

webrtc/call/rtp_stream_receiver_controller.cc

+/*
+ *  Copyright (c) 2017 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/call/rtp_stream_receiver_controller.h"
+#include "webrtc/base/ptr_util.h"
+
+namespace webrtc {
+
+RtpStreamReceiverController::Receiver::Receiver(
+    RtpStreamReceiverController* controller,
+    uint32_t ssrc,
+    RtpPacketSinkInterface* sink)
+    : controller_(controller), sink_(sink) {
+  controller_->AddSink(ssrc, sink_);
+}
+
+RtpStreamReceiverController::Receiver::~Receiver() {
+  // Don't require return value > 0, since for RTX we currently may
+  // have multiple Receiver objects with the same sink.
+  // TODO(nisse): Consider adding a DCHECK when RtxReceiveStream is wired up.
+  controller_->RemoveSink(sink_);
+}
+
+std::unique_ptr<RtpStreamReceiverInterface>
+RtpStreamReceiverController::CreateReceiver(
+    uint32_t ssrc,
+    RtpPacketSinkInterface* sink) {
+  return rtc::MakeUnique<Receiver>(this, ssrc, sink);
+}
+
+bool RtpStreamReceiverController::OnRtpPacket(const RtpPacketReceived& packet) {

[the sun, 2017/06/16 13:37:39]

Please add thread checkers so we can lock down usage as much as possible with
the longer term goal of removing ad-hoc lock usage.

[nisse-webrtc, 2017/06/16 14:33:25]

I'll try to sort it out. But I kind-of expect that OnRtpPacket and
AddSink/RemoveSink used on different threads.

[the sun, 2017/06/16 15:00:13]

Yes, we just want to document that.

[nisse-webrtc, 2017/06/20 09:04:35]

Added thread checkers, and it seems to pass tests.

+  rtc::CritScope cs(&lock_);
+  return demuxer_.OnRtpPacket(packet);
+}
+
+void RtpStreamReceiverController::AddSink(uint32_t ssrc,
+                                          RtpPacketSinkInterface* sink) {
+  rtc::CritScope cs(&lock_);
+  return demuxer_.AddSink(ssrc, sink);
+}
+
+size_t RtpStreamReceiverController::RemoveSink(
+    const RtpPacketSinkInterface* sink) {
+  rtc::CritScope cs(&lock_);
+  return demuxer_.RemoveSink(sink);
+}
+
+}  // namespace webrtc