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/testsupport/unittest_utils.h b/webrtc/test/testsupport/unittest_utils.h
index bb244a4..ba6db98 100644
--- a/webrtc/test/testsupport/unittest_utils.h
+++ b/webrtc/test/testsupport/unittest_utils.h
@@ -14,8 +14,8 @@
 namespace webrtc {
 namespace test {
 
-const int kPacketSizeInBytes = 1500;
-const int kPacketDataLength = kPacketSizeInBytes * 2 + 1;
+const size_t kPacketSizeInBytes = 1500;
+const size_t kPacketDataLength = kPacketSizeInBytes * 2 + 1;
 const int kPacketDataNumberOfPackets = 3;
 
 // A base test fixture for packet related tests. Contains