Add sanity check for decreasing RTP timestamp in RtpToNtpMs.

webrtc/system_wrappers/source/rtp_to_ntp_unittest.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 118 matching lines @@
   rtcp.push_front(RtcpMeasurement(ntp_sec, ntp_frac, timestamp));
   ntp_frac += kOneMsInNtpFrac;
   timestamp -= kTimestampTicksPerMs;
   rtcp.push_front(RtcpMeasurement(ntp_sec, ntp_frac, timestamp));
   ntp_frac += kOneMsInNtpFrac;
   timestamp += 2*kTimestampTicksPerMs;
   int64_t timestamp_in_ms = -1;
   EXPECT_FALSE(RtpToNtpMs(timestamp, rtcp, &timestamp_in_ms));
 }
 
+TEST(RtpToNtpTests, FailsForDecreasingRtpTimestamp) {
+  const uint32_t kNtpSec1 = 3683354930;
+  const uint32_t kNtpFrac1 = 699925050;
+  const uint32_t kTimestamp1 = 2192705742;
+  const uint32_t kNtpSec2 = kNtpSec1;
+  const uint32_t kNtpFrac2 = kNtpFrac1 + kOneMsInNtpFrac;
+  const uint32_t kTimestamp2 = kTimestamp1 - kTimestampTicksPerMs;
+  RtcpList rtcp;
+  rtcp.push_front(RtcpMeasurement(kNtpSec1, kNtpFrac1, kTimestamp1));
+  rtcp.push_front(RtcpMeasurement(kNtpSec2, kNtpFrac2, kTimestamp2));
+  int64_t timestamp_in_ms = -1;
+  EXPECT_FALSE(RtpToNtpMs(kTimestamp1, rtcp, &timestamp_in_ms));
+}
+
 TEST(UpdateRtcpListTests, InjectRtcpSrWithEqualNtp) {
   RtcpList rtcp;
   uint32_t ntp_sec = 0;
   uint32_t ntp_frac = 2;
   uint32_t timestamp = 0x12345678;
 
   bool new_sr;
   EXPECT_TRUE(UpdateRtcpList(ntp_sec, ntp_frac, timestamp, &rtcp, &new_sr));
   EXPECT_TRUE(new_sr);
 
@@ skipping 20 matching lines @@
 TEST(UpdateRtcpListTests, InjectRtcpSrWithZeroNtpFails) {
   RtcpList rtcp;
   uint32_t ntp_sec = 0;
   uint32_t ntp_frac = 0;
   uint32_t timestamp = 0x12345678;
 
   bool new_sr;
   EXPECT_FALSE(UpdateRtcpList(ntp_sec, ntp_frac, timestamp, &rtcp, &new_sr));
 }
 };  // namespace webrtc