Clear reference time after SetMediaTime in video-only time source.

media/base/wall_clock_time_source.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/wall_clock_time_source.h"
 
 #include "base/logging.h"
 
 namespace media {
 
@@ skipping 32 matching lines @@
   }
 
   playback_rate_ = playback_rate;
 }
 
 void WallClockTimeSource::SetMediaTime(base::TimeDelta time) {
   DVLOG(1) << __func__ << "(" << time.InMicroseconds() << ")";
   base::AutoLock auto_lock(lock_);
   CHECK(!ticking_);
   base_timestamp_ = time;
+  reference_time_ = base::TimeTicks();
 }
 
 base::TimeDelta WallClockTimeSource::CurrentMediaTime() {
   base::AutoLock auto_lock(lock_);
   return CurrentMediaTime_Locked();
 }
 
 bool WallClockTimeSource::GetWallClockTimes(
     const std::vector<base::TimeDelta>& media_timestamps,
     std::vector<base::TimeTicks>* wall_clock_times) {
@@ skipping 22 matching lines @@
   if (!ticking_ || !playback_rate_)
     return base_timestamp_;
 
   base::TimeTicks now = tick_clock_->NowTicks();
   return base_timestamp_ +
          base::TimeDelta::FromMicroseconds(
              (now - reference_time_).InMicroseconds() * playback_rate_);
 }
 
 }  // namespace media