Replace uses of raw uint32's with a type-checked RtpTimeTicks data type.

media/cast/net/rtp/rtp_parser.h

Index: media/cast/net/rtp/rtp_parser.h
diff --git a/media/cast/net/rtp/rtp_parser.h b/media/cast/net/rtp/rtp_parser.h
index f86a285e0b16ea4870fa0caa97a3609cf368a3e7..282bca005ada38aa830bf66369a80ba5ba9baf02 100644
--- a/media/cast/net/rtp/rtp_parser.h
+++ b/media/cast/net/rtp/rtp_parser.h
@@ -42,6 +42,11 @@ class RtpParser {
  private:
   const uint32_t expected_sender_ssrc_;
   const uint8_t expected_payload_type_;
+
+  // Tracks recently-parsed RTP timestamps so that it can expand the truncated
+  // values found in packets.
+  RtpTimeTicks last_parsed_rtp_timestamp_;
+
   FrameIdWrapHelper frame_id_wrap_helper_;
 
   DISALLOW_COPY_AND_ASSIGN(RtpParser);