Add new codec for FlexFEC.

webrtc/api/webrtcsdp.cc

Index: webrtc/api/webrtcsdp.cc
diff --git a/webrtc/api/webrtcsdp.cc b/webrtc/api/webrtcsdp.cc
index 771e06855d7709d6d0280e5b060ac3a3127cd0e8..b7ef28e38d421c554fb8908dbeccb3ab0ac30138 100644
--- a/webrtc/api/webrtcsdp.cc
+++ b/webrtc/api/webrtcsdp.cc
@@ -1598,7 +1598,8 @@ bool IsFmtpParam(const std::string& name) {
       kCodecParamAssociatedPayloadType,
       cricket::kH264FmtpPacketizationMode,
       cricket::kH264FmtpLevelAsymmetryAllowed,
-      cricket::kH264FmtpProfileLevelId};
+      cricket::kH264FmtpProfileLevelId,
+      cricket::kFlexfecFmtpRepairWindow};
   for (size_t i = 0; i < arraysize(kFmtpParams); ++i) {
     if (name.compare(kFmtpParams[i]) == 0) {
       return true;