Remove unused SPDY/3 enum values.

net/http/http_server_properties.cc

Index: net/http/http_server_properties.cc
diff --git a/net/http/http_server_properties.cc b/net/http/http_server_properties.cc
index 8b8b50cdea2634d0c98321ca08a9b84d477f6c71..fc6281e43b5b9c11405ab98936e04a1b668d7c36 100644
--- a/net/http/http_server_properties.cc
+++ b/net/http/http_server_properties.cc
@@ -20,7 +20,6 @@ namespace {
 // The order of these strings much match the order of the enum definition
 // for AlternateProtocol.
 const char* const kAlternateProtocolStrings[] = {
-    "npn-spdy/3",
     "npn-spdy/3.1",
     "npn-h2",
     "quic"};
@@ -49,7 +48,6 @@ bool IsAlternateProtocolValid(AlternateProtocol protocol) {
 
 const char* AlternateProtocolToString(AlternateProtocol protocol) {
   switch (protocol) {
-    case NPN_SPDY_3:
     case NPN_SPDY_3_1:
     case NPN_HTTP_2:
     case QUIC:
@@ -75,8 +73,6 @@ AlternateProtocol AlternateProtocolFromString(const std::string& str) {
 
 AlternateProtocol AlternateProtocolFromNextProto(NextProto next_proto) {
   switch (next_proto) {
-    case kProtoSPDY3:
-      return NPN_SPDY_3;
     case kProtoSPDY31:
       return NPN_SPDY_3_1;
     case kProtoHTTP2: