Fix FecTest.FlexfecTest flakiness caused by seq. num. wraparound.

webrtc/modules/rtp_rtcp/test/testFec/test_fec.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 117 matching lines @@
   fclose(random_seed_file);
   random_seed_file = nullptr;
 
   uint16_t seq_num = 0;
   uint32_t timestamp = random.Rand<uint32_t>();
   const uint32_t media_ssrc = random.Rand(1u, 0xfffffffe);
   uint32_t fec_ssrc;
   uint16_t fec_seq_num_offset;
   if (use_flexfec) {
     fec_ssrc = random.Rand(1u, 0xfffffffe);
-    fec_seq_num_offset = random.Rand<uint16_t>();
+    fec_seq_num_offset = random.Rand(0, 1 << 15);
   } else {
     fec_ssrc = media_ssrc;
     fec_seq_num_offset = 0;
   }
 
   std::unique_ptr<ForwardErrorCorrection> fec;
   if (use_flexfec) {
     fec = ForwardErrorCorrection::CreateFlexfec(fec_ssrc, media_ssrc);
   } else {
     RTC_DCHECK_EQ(media_ssrc, fec_ssrc);
@@ skipping 309 matching lines @@
   }    // loop over mask types
 
   // Have DecodeFec clear the recovered packet list.
   fec->ResetState(&recovered_packet_list);
   ASSERT_TRUE(recovered_packet_list.empty())
       << "Recovered packet list is not empty";
 }
 
 // Too slow to finish before timeout on iOS. See webrtc:4755.
 #if defined(WEBRTC_IOS)
-#define MAYBE_UlpecTest DISABLED_UlpecTest
+#define MAYBE_UlpfecTest DISABLED_UlpfecTest
 #define MAYBE_FlexfecTest DISABLED_FlexfecTest
 #else
-#define MAYBE_UlpecTest UlpecTest
+#define MAYBE_UlpfecTest UlpfecTest
 #define MAYBE_FlexfecTest FlexfecTest
 #endif
-TEST(FecTest, MAYBE_UlpecTest) {
+TEST(FecTest, MAYBE_UlpfecTest) {
   RunTest(false);
 }
 
 TEST(FecTest, MAYBE_FlexfecTest) {
   RunTest(true);
 }
 
 }  // namespace test
 }  // namespace webrtc