Remove hardcoded kValueSizeBytes values from variable-length header extensions.

webrtc/modules/rtp_rtcp/source/flexfec_sender_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.
  */
 
@@ skipping 236 matching lines @@
   EXPECT_TRUE(fec_packet->HasExtension<AbsoluteSendTime>());
   EXPECT_TRUE(fec_packet->HasExtension<TransmissionOffset>());
   EXPECT_TRUE(fec_packet->HasExtension<TransportSequenceNumber>());
 }
 
 TEST(FlexfecSenderTest, MaxPacketOverhead) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   FlexfecSender sender(kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoRtpHeaderExtensions, &clock);
 
-  EXPECT_EQ(kFlexfecMaxHeaderSize, sender.MaxPacketOverhead());
+  EXPECT_EQ(kFlexfecMaxHeaderSize,
+            sender.MaxPacketOverhead({} /* extension_sizes */));
 }
 
 }  // namespace webrtc