Remove support for "npn-h2" and "npn-spdy/3.1" persisted values.

net/socket/next_proto.cc

Index: net/socket/next_proto.cc
diff --git a/net/socket/next_proto.cc b/net/socket/next_proto.cc
index 7ec7c1d68d09537581bb04452dec60fd63a689c3..b637f978d5f8a02c95f8e7db9b4816f633b999b2 100644
--- a/net/socket/next_proto.cc
+++ b/net/socket/next_proto.cc
@@ -9,11 +9,7 @@ namespace net {
 NextProto NextProtoFromString(base::StringPiece proto_string) {
   if (proto_string == "http1.1" || proto_string == "http/1.1")
     return kProtoHTTP11;
-  // "npn-h2" and "npn-spdy/3.1" are accepted here so that persisted
-  // settings with the old string can be loaded from disk.
-  // TODO(bnc):  Remove around 2016 December.
-  if (proto_string == "h2" || proto_string == "npn-h2" ||
-      proto_string == "npn-spdy/3.1") {
+  if (proto_string == "h2") {
     return kProtoHTTP2;
   }
   if (proto_string == "quic")