Delete class NullRtpData and function NullObjectRtpData

webrtc/modules/rtp_rtcp/source/rtp_receiver_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_unittest.cc b/webrtc/modules/rtp_rtcp/source/rtp_receiver_unittest.cc
index a68f06e6848dcd3c3ad5433ad74aceeeb2d788ab..363659efe7f256317b7ebeec4abffff7ca0f5929 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_unittest.cc
@@ -46,7 +46,7 @@ class RtpReceiverTest : public ::testing::Test {
       : fake_clock_(123456),
         rtp_receiver_(
             RtpReceiver::CreateAudioReceiver(&fake_clock_,
-                                             nullptr,
+                                             &null_rtp_data_,
                                              nullptr,
                                              &rtp_payload_registry_)) {
     CodecInst voice_codec = {};
@@ -73,6 +73,7 @@ class RtpReceiverTest : public ::testing::Test {
   }
 
   SimulatedClock fake_clock_;
+  NullRtpData null_rtp_data_;
   RTPPayloadRegistry rtp_payload_registry_;
   std::unique_ptr<RtpReceiver> rtp_receiver_;
 };