Revert of Remove unnecessary interface TelephoneEventHandler

webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h b/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h
index 1a3b41b9d9747243e5ec8e1455c30c45d8fffe1f..a8aaf5da18b657ec628c57f0f9c003d4d6ecbc30 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.h
@@ -33,6 +33,8 @@
                          int64_t timestamp,
                          bool is_first_packet) override;
 
+  TelephoneEventHandler* GetTelephoneEventHandler() override { return NULL; }
+
   int GetPayloadTypeFrequency() const override;
 
   RTPAliveType ProcessDeadOrAlive(uint16_t last_payload_length) const override;