Changed Text Sample to use int64_t so that it will use the same type for time as Media Sample. Change-Id: I4cfbfdc60c37bb511517993976cd1a459bdf6667
Renamed the webvtt segmenter to text chunker as there is nothing webvtt specific in the code. Change-Id: I0111c50d545fa168d945b39bc8a78c46c62678be