Add read support of RtpStreamId/RepairedRtpStreamId header extensions.

webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc b/webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc
index bdf3aba7b00013ae8c20d3e0db6a732652f72659..ab73bcf0dbf75d9bfa92f8b297a8a7237095eccf 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_packet_unittest.cc
@@ -363,4 +363,30 @@ TEST(RtpPacketTest, ParseWithoutExtensionManager) {
   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