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

media/cast/BUILD.gn

 # 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.
 
 component("cast") {
   deps = [
     ":sender",
     ":receiver",
   ]
 }
@@ skipping 54 matching lines @@
     "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_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_builder.cc",
+    "net/rtcp/rtcp_builder.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",
@@ skipping 135 matching lines @@
     "logging/serialize_deserialize_test.cc",
     "logging/logging_impl_unittest.cc",
     "logging/logging_raw_unittest.cc",
     "logging/receiver_time_offset_estimator_impl_unittest.cc",
     "logging/simple_event_subscriber_unittest.cc",
     "logging/stats_event_subscriber_unittest.cc",
     "net/cast_transport_sender_impl_unittest.cc",
     "net/pacing/mock_paced_packet_sender.cc",
     "net/pacing/mock_paced_packet_sender.h",
     "net/pacing/paced_sender_unittest.cc",
-    "net/rtcp/rtcp_sender_unittest.cc",
+    "net/rtcp/rtcp_builder_unittest.cc",
     "net/rtcp/rtcp_unittest.cc",
     "net/rtcp/rtcp_utility_unittest.cc",
     "net/rtcp/receiver_rtcp_event_subscriber_unittest.cc",
 # TODO(miu): The following two are test utility modules.  Rename/move the files.
     "net/rtcp/test_rtcp_packet_builder.cc",
     "net/rtcp/test_rtcp_packet_builder.h",
     "net/rtp/cast_message_builder_unittest.cc",
     "net/rtp/frame_buffer_unittest.cc",
     "net/rtp/framer_unittest.cc",
     "net/rtp/mock_rtp_payload_feedback.cc",
@@ skipping 67 matching lines @@
   sources = [
     "test/utility/udp_proxy_main.cc",
   ]
 
   deps = [
     ":test_support",
     "//base",
     "//net",
   ]
 }