Makes treatment of received reports of packets lost signed.

Bug: webrtc:9598
Change-Id: I0f6ffe348585b8ec69753089652812da516d33d8
Reviewed-on: https://webrtc-review.googlesource.com/93021
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Magnus Flodman <mflodman@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24291}
diff --git a/modules/rtp_rtcp/include/rtp_rtcp_defines.h b/modules/rtp_rtcp/include/rtp_rtcp_defines.h
index 260e461..34c7428 100644
--- a/modules/rtp_rtcp/include/rtp_rtcp_defines.h
+++ b/modules/rtp_rtcp/include/rtp_rtcp_defines.h
@@ -193,7 +193,7 @@
   uint32_t sender_ssrc;  // SSRC of sender of this report.
   uint32_t source_ssrc;  // SSRC of the RTP packet sender.
   uint8_t fraction_lost;
-  uint32_t packets_lost;  // 24 bits valid.
+  int32_t packets_lost;  // 24 bits valid.
   uint32_t extended_highest_sequence_number;
   uint32_t jitter;
   uint32_t last_sender_report_timestamp;
diff --git a/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc b/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
index 91ffd73..6cd953c 100644
--- a/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
+++ b/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
@@ -441,7 +441,7 @@
 TEST_F(RtcpReceiverTest, InjectRrPacketsFromTwoRemoteSsrcs) {
   const uint32_t kSenderSsrc2 = 0x20304;
   const uint16_t kSequenceNumbers[] = {10, 12423};
-  const uint32_t kCumLost[] = {13, 555};
+  const int32_t kCumLost[] = {13, 555};
   const uint8_t kFracLost[] = {20, 11};
 
   rtcp::ReportBlock rb1;
diff --git a/modules/rtp_rtcp/test/testAPI/test_api_rtcp.cc b/modules/rtp_rtcp/test/testAPI/test_api_rtcp.cc
index b6368f7..2edebae 100644
--- a/modules/rtp_rtcp/test/testAPI/test_api_rtcp.cc
+++ b/modules/rtp_rtcp/test/testAPI/test_api_rtcp.cc
@@ -213,7 +213,7 @@
   EXPECT_EQ(test_ssrc + 1, report_blocks[0].sender_ssrc);
   EXPECT_EQ(test_ssrc, report_blocks[0].source_ssrc);
 
-  EXPECT_EQ(0u, report_blocks[0].packets_lost);
+  EXPECT_EQ(0, report_blocks[0].packets_lost);
   EXPECT_LT(0u, report_blocks[0].delay_since_last_sender_report);
   EXPECT_EQ(test_sequence_number,
             report_blocks[0].extended_highest_sequence_number);