Enable SCTP in libjingle.

third_party/usrsctp/README.chromium

Index: third_party/usrsctp/README.chromium
===================================================================
--- third_party/usrsctp/README.chromium	(revision 204288)
+++ third_party/usrsctp/README.chromium	(working copy)
@@ -8,7 +8,19 @@
 Security Critical: yes
 
 Description:
-The libjingle/webrtc uses usrsctp as the reliability layer for data channels.
+The usrsctplib provides implementation of SCTP protocol which fully supports RFC 2960
+as well as updates and enhancements from the following Internet Drafts:
+   draft-ietf-tsvwg-sctpcsum-05.txt
+   draft-ietf-tsvwg-sctpimpguide-05.txt
+   draft-ietf-tsvwg-sctpsocket-04.txt
+   draft-ietf-tsvwg-addip-sctp-05.txt
+   draft-stewart-prsctp-00.txt
+   draft-stewart-tsvwg-sctpipv6-00.txt
+   draft-iyengar-sctp-cacc-00.txt
 
 Local Modifications:
-None.
+usrsctplib provides its own SHA1 implementations as part of the library. Since chrome
+already has the support of both NSS and OPENSSL which already has the implementation
+of SHA1, Chromium will not include the SHA1 from usrsctplib.
+Overrides folder has the necessary changes to strip existing SHA1 implementation in
+usrsctplib and use OPENSSL or NSS implementation based on the platform type.