[rtp_rtcp] rtcp::Sdes moved into own file

Cleaning/Parsing will be done in the https://codereview.webrtc.org/1439553003/

BUG=webrtc:5260
R=asapersson@webrtc.org, åsapersson

Review URL: https://codereview.webrtc.org/1592763002 .

Cr-Commit-Position: refs/heads/master@{#11274}

webrtc/modules/rtp_rtcp/source/rtcp_packet/sdes.h

@@ -0,0 +1,56 @@
+/*
+ *  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.
+ *
+ */
+
+#ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_SDES_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_SDES_H_
+
+#include <string>
+#include <vector>
+
+#include "webrtc/base/basictypes.h"
+#include "webrtc/modules/rtp_rtcp/source/rtcp_packet.h"
+#include "webrtc/modules/rtp_rtcp/source/rtcp_utility.h"
+
+namespace webrtc {
+namespace rtcp {
+// Source Description (SDES) (RFC 3550).
+class Sdes : public RtcpPacket {
+ public:
+  Sdes() : RtcpPacket() {}
+
+  virtual ~Sdes() {}
+
+  bool WithCName(uint32_t ssrc, const std::string& cname);
+
+  struct Chunk {
+    uint32_t ssrc;
+    std::string name;
+    int null_octets;
+  };
+
+ protected:
+  bool Create(uint8_t* packet,
+              size_t* index,
+              size_t max_length,
+              RtcpPacket::PacketReadyCallback* callback) const override;
+
+ private:
+  static const int kMaxNumberOfChunks = 0x1f;
+
+  size_t BlockLength() const;
+
+  std::vector<Chunk> chunks_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(Sdes);
+};
+}  // namespace rtcp
+}  // namespace webrtc
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_SDES_H_