Use size_t more consistently for packet/payload lengths.

See design doc at https://docs.google.com/a/chromium.org/document/d/1I6nmE9D_BmCY-IoV6MDPY2V6WYpEI-dg2apWXTfZyUI/edit?usp=sharing for more information.

This CL was reviewed and approved in pieces in the following CLs:
https://webrtc-codereview.appspot.com/24209004/
https://webrtc-codereview.appspot.com/24229004/
https://webrtc-codereview.appspot.com/24259004/
https://webrtc-codereview.appspot.com/25109004/
https://webrtc-codereview.appspot.com/26099004/
https://webrtc-codereview.appspot.com/27069004/
https://webrtc-codereview.appspot.com/27969004/
https://webrtc-codereview.appspot.com/27989004/
https://webrtc-codereview.appspot.com/29009004/
https://webrtc-codereview.appspot.com/30929004/
https://webrtc-codereview.appspot.com/30939004/
https://webrtc-codereview.appspot.com/31999004/
Committing as TBR to the original reviewers.

BUG=chromium:81439
TEST=none
TBR=pthatcher,henrik.lundin,tina.legrand,stefan,tkchin,glaznev,kjellander,perkj,mflodman,henrika,asapersson,niklas.enbom

Review URL: https://webrtc-codereview.appspot.com/23129004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7726 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/test/rtcp_packet_parser.cc b/webrtc/test/rtcp_packet_parser.cc
index 558bee3..391be85 100644
--- a/webrtc/test/rtcp_packet_parser.cc
+++ b/webrtc/test/rtcp_packet_parser.cc
@@ -17,7 +17,7 @@
 
 RtcpPacketParser::~RtcpPacketParser() {}
 
-void RtcpPacketParser::Parse(const void *data, int len) {
+void RtcpPacketParser::Parse(const void *data, size_t len) {
   const uint8_t* packet = static_cast<const uint8_t*>(data);
   RTCPUtility::RTCPParserV2 parser(packet, len, true);
   for (RTCPUtility::RTCPPacketTypes type = parser.Begin();