Add a whitelist for QUIC hosts.

net/http/http_stream_factory_impl.h

Index: net/http/http_stream_factory_impl.h
diff --git a/net/http/http_stream_factory_impl.h b/net/http/http_stream_factory_impl.h
index 5d8a2060868aea9a394e50422b20e750bc1cb172..799398f539e586d1bb4f37c359ab16dc01a4e196 100644
--- a/net/http/http_stream_factory_impl.h
+++ b/net/http/http_stream_factory_impl.h
@@ -118,6 +118,10 @@ class NET_EXPORT_PRIVATE HttpStreamFactoryImpl : public HttpStreamFactory {
   // Called when the Preconnect completes. Used for testing.
   virtual void OnPreconnectsCompleteInternal() {}
 
+  // Returns true if QUIC is whitelisted for |host|, which should be
+  // the result of calling ApplyHostMappingRules().
+  bool IsQuicWhitelistedForHost(const std::string& host);
+
   HttpNetworkSession* const session_;
 
   // All Requests are handed out to clients. By the time HttpStreamFactoryImpl