Fixed time moving backwards in the AudioCodingModule.

webrtc/modules/audio_coding/test/TestVADDTX.h

Index: webrtc/modules/audio_coding/test/TestVADDTX.h
diff --git a/webrtc/modules/audio_coding/test/TestVADDTX.h b/webrtc/modules/audio_coding/test/TestVADDTX.h
index 893babc4e0a8c6afc36605b0789f526ddf32eb12..b7e987137c18c5250047685d508bc8defa4904a7 100644
--- a/webrtc/modules/audio_coding/test/TestVADDTX.h
+++ b/webrtc/modules/audio_coding/test/TestVADDTX.h
@@ -72,6 +72,7 @@ class TestVadDtx : public ACMTest {
   std::unique_ptr<AudioCodingModule> acm_receive_;
   std::unique_ptr<Channel> channel_;
   std::unique_ptr<ActivityMonitor> monitor_;
+  uint32_t time_stamp_ = 0x12345678;
 };
 
 // TestWebRtcVadDtx is to verify that the WebRTC VAD/DTX perform as they should.