Revert of Reset NACK/ACK list when parsing a new RTCP packet. The NAC…

…K/ACK frames/packets list need to be res… (patchset #1 id:1 of https://codereview.chromium.org/1875433002/ )

Reason for revert:
This change needs to be slightly modified since M50 does not have the |received_later_frames| set.

Original issue's description:
> Reset NACK/ACK list when parsing a new RTCP packet. The NACK/ACK frames/packets list need to be reset before parsing each RTCP packet as the parser is shared by all RTCP packets on sender side. This caused the performance regression and potentially video freezing as well.
>
> BUG=600527
>
> Review URL: https://codereview.chromium.org/1853253003
>
> Cr-Commit-Position: refs/heads/master@{#385046}
> (cherry picked from commit 411ea14)
>
> Committed: https://chromium.googlesource.com/chromium/src/+/e877754f597c1c2fa8ff411be0c2c6ade0cd6c9f

[email protected]
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=600527

Review URL: https://codereview.chromium.org/1869163002

Cr-Commit-Position: refs/branch-heads/2661@{#512}
Cr-Branched-From: ef6f6ae-refs/heads/master@{#378081}

media/cast/net/rtcp/rtcp_utility.cc

@@ -291,8 +291,6 @@ bool RtcpParser::ParseFeedbackCommon(base::BigEndianReader* reader,
   // Please note, this frame_id is still only 8-bit!
   cast_message_.ack_frame_id = last_frame_id;
 
-  cast_message_.missing_frames_and_packets.clear();
-  cast_message_.received_later_frames.clear();
   for (size_t i = 0; i < number_of_lost_fields; i++) {
     uint8_t frame_id;
     uint16_t packet_id;