Implemented a proper clock for audio/video synchronization.

media/base/pipeline_impl.h

Index: media/base/pipeline_impl.h
diff --git a/media/base/pipeline_impl.h b/media/base/pipeline_impl.h
index 4eed436b64cff37ea41f12d1ae175ffc377b7274..02c8bcef8855792a0590a8dbdd994d8052f4c395 100644
--- a/media/base/pipeline_impl.h
+++ b/media/base/pipeline_impl.h
@@ -15,6 +15,7 @@
 #include "base/ref_counted.h"
 #include "base/thread.h"
 #include "base/time.h"
+#include "media/base/clock_impl.h"
 #include "media/base/filter_host.h"
 #include "media/base/pipeline.h"
 
@@ -276,8 +277,10 @@ class PipelineImpl : public Pipeline, public FilterHost {
   // the filters.
   float playback_rate_;
 
-  // Current playback time.  Set by filters.
-  base::TimeDelta time_;
+  // Reference clock.  Keeps track of current playback time.  Uses system
+  // clock and linear interpolation, but can have its time manually set
+  // by filters.
+  ClockImpl clock_;
 
   // Status of the pipeline.  Initialized to PIPELINE_OK which indicates that
   // the pipeline is operating correctly. Any other value indicates that the