Fixed flaky VideoSendStreamTest::SupportsAbsoluteSendTime

webrtc/video/video_send_stream_tests.cc

 /*
  *  Copyright (c) 2013 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.
  */
 #include <algorithm>  // max
@@ skipping 118 matching lines @@
           kRtpExtensionAbsoluteSendTime, test::kAbsSendTimeExtensionId));
     }
 
     Action OnSendRtp(const uint8_t* packet, size_t length) override {
       RTPHeader header;
       EXPECT_TRUE(parser_->Parse(packet, length, &header));
 
       EXPECT_FALSE(header.extension.hasTransmissionTimeOffset);
       EXPECT_TRUE(header.extension.hasAbsoluteSendTime);
       EXPECT_EQ(header.extension.transmissionTimeOffset, 0);
-      EXPECT_GT(header.extension.absoluteSendTime, 0u);
-      observation_complete_.Set();
+      if (header.extension.absoluteSendTime != 0) {
+        // Wait for at least one packet with a non-zero send time. The send time
+        // is a 16-bit value derived from the system clock, and it is valid
+        // for a packet to have a zero send time. To tell that from an
+        // unpopulated value we'll wait for a packet with non-zero send time.
+        observation_complete_.Set();
+      } else {
+        LOG(LS_WARNING) << "Got a packet with zero absoluteSendTime, waiting"
+                           " for another packet...";
+      }
 
       return SEND_PACKET;
     }
 
     void ModifyVideoConfigs(
         VideoSendStream::Config* send_config,
         std::vector<VideoReceiveStream::Config>* receive_configs,
         VideoEncoderConfig* encoder_config) override {
       send_config->rtp.extensions.clear();
       send_config->rtp.extensions.push_back(RtpExtension(
@@ skipping 2374 matching lines @@
         observation_complete_.Set();
       }
     }
   } test;
 
   RunBaseTest(&test);
 }
 #endif  // !defined(RTC_DISABLE_VP9)
 
 }  // namespace webrtc