Delete class NullRtpData and function NullObjectRtpData

webrtc/modules/rtp_rtcp/source/rtcp_sender_unittest.cc

 /*
  *  Copyright (c) 2012 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 179 matching lines @@
       uint32_t ssrc,
       const RtcpPacketTypeCounter& packet_counter) override {
     ssrc_ = ssrc;
     counter_ = packet_counter;
   }
   uint32_t ssrc_;
   RtcpPacketTypeCounter counter_;
 };
 
 class TestTransport : public Transport,
-                      public NullRtpData {
+                      public RtpData {
  public:
   TestTransport() {}
 
   bool SendRtp(const uint8_t* /*data*/,
                size_t /*len*/,
                const PacketOptions& options) override {
     return false;
   }
   bool SendRtcp(const uint8_t* data, size_t len) override {
     parser_.Parse(data, len);
@@ skipping 625 matching lines @@
       const rtcp::TargetBitrate::BitrateItem& item = bitrates[index];
       EXPECT_EQ(sl, item.spatial_layer);
       EXPECT_EQ(tl, item.temporal_layer);
       EXPECT_EQ(start_bitrate_bps + (tl * 20000),
                 item.target_bitrate_kbps * 1000);
     }
   }
 }
 
 }  // namespace webrtc