Add read support of RtpStreamId/RepairedRtpStreamId header extensions.

webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc

 /*
  *  Copyright (c) 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/modules/rtp_rtcp/source/rtp_packet_received.h"
@@ skipping 345 matching lines @@
   EXPECT_TRUE(packet.HasRawExtension(kTransmissionOffsetExtensionId));
 
   int32_t time_offset = 0;
   auto raw_extension = packet.GetRawExtension(kTransmissionOffsetExtensionId);
   EXPECT_EQ(raw_extension.size(), TransmissionOffset::kValueSizeBytes);
   EXPECT_TRUE(TransmissionOffset::Parse(raw_extension, &time_offset));
 
   EXPECT_EQ(time_offset, kTimeOffset);
 }
 
+TEST(RtpPacketTest, ParseDynamicSizeExtension) {
+  // clang-format off
+  const uint8_t kPacket[] = {
+    0x90, kPayloadType, 0x00, kSeqNum,
+    0x65, 0x43, 0x12, 0x78,  // kTimestamp.
+    0x12, 0x34, 0x56, 0x78,  // kSsrc.
+    0xbe, 0xde, 0x00, 0x02,  // Extensions block of size 2x32bit words.
+    0x21, 'r', 'x',          // Extension with id = 2, size = (1+1).
+    0x12, 'R', 'i', 'd',     // Extension with id = 1, size = (2+1).
+    0x00};  // Extension padding.
+  // clang-format on
+  RtpPacketReceived::ExtensionManager extensions;
+  extensions.Register<RtpStreamId>(1);
+  extensions.Register<RepairRtpStreamId>(2);
+  RtpPacketReceived packet(&extensions);
+  ASSERT_TRUE(packet.Parse(kPacket, sizeof(kPacket)));
+
+  std::string rid;
+  EXPECT_TRUE(packet.GetExtension<RtpStreamId>(&rid));
+  EXPECT_EQ(rid, "Rid");
+
+  std::string repair_rid;
+  EXPECT_TRUE(packet.GetExtension<RepairRtpStreamId>(&repair_rid));
+  EXPECT_EQ(repair_rid, "rx");
+}
+
 }  // namespace webrtc