Cast: Re-factor rtcp_sender.cc into rtcp_builder.cc and do some cleanup

media/cast/cast.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'include_tests%': 1,
     'chromium_code': 1,
   },
   'conditions': [
@@ skipping 166 matching lines @@
       'sources': [
         'net/cast_transport_config.cc',
         'net/cast_transport_config.h',
         'net/cast_transport_defines.h',
         'net/cast_transport_sender.h',
         'net/cast_transport_sender_impl.cc',
         'net/cast_transport_sender_impl.h',
         'net/pacing/paced_sender.cc',
         'net/pacing/paced_sender.h',
         'net/rtcp/receiver_rtcp_event_subscriber.cc',
+        'net/rtcp/rtcp_builder.cc',
+        'net/rtcp/rtcp_builder.h',
         'net/rtcp/rtcp_defines.cc',
         'net/rtcp/rtcp_defines.h',
         'net/rtcp/rtcp.h',
         'net/rtcp/rtcp.cc',
-        'net/rtcp/rtcp_sender.cc',
-        'net/rtcp/rtcp_sender.h',
         'net/rtcp/rtcp_utility.cc',
         'net/rtcp/rtcp_utility.h',
         'net/rtp/packet_storage.cc',
         'net/rtp/packet_storage.h',
         'net/rtp/rtp_packetizer.cc',
         'net/rtp/rtp_packetizer.h',
         'net/rtp/rtp_sender.cc',
         'net/rtp/rtp_sender.h',
         'net/udp_transport.cc',
         'net/udp_transport.h',
       ], # source
     },
   ],
 }