Switch to using media::TimeSource inside media::RendererImpl.

media/base/wall_clock_time_source.cc

Index: media/base/wall_clock_time_source.cc
diff --git a/media/base/wall_clock_time_source.cc b/media/base/wall_clock_time_source.cc
index 67b16f717952c29dc1d8e7fe5abb174a0ec60bef..ea7ac5dfd453ff0b09477b0a38721473dfcdf9bf 100644
--- a/media/base/wall_clock_time_source.cc
+++ b/media/base/wall_clock_time_source.cc
@@ -57,6 +57,10 @@ base::TimeDelta WallClockTimeSource::CurrentMediaTime() {
              (now - reference_wall_ticks_).InMicroseconds() * playback_rate_);
 }
 
+base::TimeDelta WallClockTimeSource::ApproximateCurrentMediaTime() {
+  return CurrentMediaTime();
+}
+
 void WallClockTimeSource::SetTickClockForTesting(
     scoped_ptr<base::TickClock> tick_clock) {
   tick_clock_.swap(tick_clock);