Respect QuicAllowed policy for new streams

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index ce4011f8e71dae9e9350c9b89d672fc1574aa62a..9d5e9a293285c0dc9d27bd400863ca012ce1b2a9 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -439,6 +439,9 @@ const char kDnsPrefetchingStartupList[] = "dns_prefetching.startup_list";
 const char kDnsPrefetchingHostReferralList[] =
     "dns_prefetching.host_referral_list";
 
+// Controls if the QUIC protocol is allowed.
+const char kQuicAllowed[] = "net.quic_allowed";
+
 // Prefs for persisting HttpServerProperties.
 const char kHttpServerProperties[] = "net.http_server_properties";