Introduce DecodeTimestamp class to make it easier to distiguish presentation and decode timestamps.

media/formats/mp2t/es_parser_adts.h

Index: media/formats/mp2t/es_parser_adts.h
diff --git a/media/formats/mp2t/es_parser_adts.h b/media/formats/mp2t/es_parser_adts.h
index 03c90110e76704135b293f435c199b3e0300b912..aa91f8559ac898ca2b881bf031e15d53af3f6841 100644
--- a/media/formats/mp2t/es_parser_adts.h
+++ b/media/formats/mp2t/es_parser_adts.h
@@ -37,7 +37,7 @@ class EsParserAdts : public EsParser {
   // EsParser implementation.
   virtual bool Parse(const uint8* buf, int size,
                      base::TimeDelta pts,
-                     base::TimeDelta dts) OVERRIDE;
+                     DecodeTimestamp dts) OVERRIDE;
   virtual void Flush() OVERRIDE;
   virtual void Reset() OVERRIDE;
 
@@ -92,4 +92,3 @@ class EsParserAdts : public EsParser {
 }  // namespace media
 
 #endif
-