Delete RTCInboundRTPStreamStats::fraction_lost

And delete corresponding plumbing via the internal stats attribute
MediaReceiverInfo::fraction_lost. The latter attribute is not deleted
yet, since downstream projects have to be updated first.

Bug: webrtc:10744
Change-Id: Id5401aeee7e5637a406ddf2fa33fbfe336abec9f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/143178
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Oskar Sundbom <ossu@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28385}

stats/rtcstats_objects.cc

@@ -602,7 +602,6 @@ WEBRTC_RTCSTATS_IMPL(
     &packets_lost,
     &last_packet_received_timestamp,
     &jitter,
-    &fraction_lost,
     &round_trip_time,
     &packets_discarded,
     &packets_repaired,
@@ -632,7 +631,6 @@ RTCInboundRTPStreamStats::RTCInboundRTPStreamStats(std::string&& id,
       packets_lost("packetsLost"),
       last_packet_received_timestamp("lastPacketReceivedTimestamp"),
       jitter("jitter"),
-      fraction_lost("fractionLost"),
       round_trip_time("roundTripTime"),
       packets_discarded("packetsDiscarded"),
       packets_repaired("packetsRepaired"),
@@ -657,7 +655,6 @@ RTCInboundRTPStreamStats::RTCInboundRTPStreamStats(
       packets_lost(other.packets_lost),
       last_packet_received_timestamp(other.last_packet_received_timestamp),
       jitter(other.jitter),
-      fraction_lost(other.fraction_lost),
       round_trip_time(other.round_trip_time),
       packets_discarded(other.packets_discarded),
       packets_repaired(other.packets_repaired),