[Cast] Clean-up RtpCastHeader and RtpParser, removing the last WebRTC dependency.

media/cast/rtp_receiver/rtp_receiver_defines.cc

Index: media/cast/rtp_receiver/rtp_receiver_defines.cc
diff --git a/media/cast/rtp_receiver/rtp_receiver_defines.cc b/media/cast/rtp_receiver/rtp_receiver_defines.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e42b2b733c7ddd5a2b71de5e3fb3d4b9e04290b8
--- /dev/null
+++ b/media/cast/rtp_receiver/rtp_receiver_defines.cc
@@ -0,0 +1,25 @@
+// Copyright 2014 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 "media/cast/rtp_receiver/rtp_receiver_defines.h"
+
+namespace media {
+namespace cast {
+
+RtpCastHeader::RtpCastHeader()
+    : marker(false),
+      payload_type(0),
+      sequence_number(0),
+      rtp_timestamp(0),
+      sender_ssrc(0),
+      is_key_frame(false),
+      frame_id(0),
+      packet_id(0),
+      max_packet_id(0),
+      reference_frame_id(0) {}
+
+RtpPayloadFeedback::~RtpPayloadFeedback() {}
+
+}  // namespace cast
+}  // namespace media