Delete unused method RtpRtcp::GetRtpPacketLossStats

It was introduced, together with the PacketLossStats class, in cl
https://codereview.webrtc.org/1198853004 (#9568). It is unused in webrtc,
but there's downstream usage of the PacketLossStats class, which
should perhaps be moved or deleted in a later cl.

Bug: None
Change-Id: I17a3d5c8748f2cc9809c438630cbe8ab680466c4
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/140042
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28153}

modules/rtp_rtcp/include/rtp_rtcp_defines.h

@@ -346,19 +346,6 @@ class RtcpRttStats {
   virtual ~RtcpRttStats() {}
 };
 
-// Statistics about packet loss for a single directional connection. All values
-// are totals since the connection initiated.
-struct RtpPacketLossStats {
-  // The number of packets lost in events where no adjacent packets were also
-  // lost.
-  uint64_t single_packet_loss_count;
-  // The number of events in which more than one adjacent packet was lost.
-  uint64_t multiple_packet_loss_event_count;
-  // The number of packets lost in events where more than one adjacent packet
-  // was lost.
-  uint64_t multiple_packet_loss_packet_count;
-};
-
 class RtpPacketSender {
  public:
   RtpPacketSender() {}