Enable QUIC for proxies based on Finch config and command line switch.

net/quic/quic_network_transaction_unittest.cc

Index: net/quic/quic_network_transaction_unittest.cc
diff --git a/net/quic/quic_network_transaction_unittest.cc b/net/quic/quic_network_transaction_unittest.cc
index 3c85ca4b44002f45a8a71212defb8c278ddbb283..7a745687d419af156d4e3ea3b6989d8091c65923 100644
--- a/net/quic/quic_network_transaction_unittest.cc
+++ b/net/quic/quic_network_transaction_unittest.cc
@@ -420,6 +420,7 @@ TEST_P(QuicNetworkTransactionTest, ForceQuic) {
 }
 
 TEST_P(QuicNetworkTransactionTest, QuicProxy) {
+  params_.enable_quic_for_proxies = true;
   proxy_service_.reset(
       ProxyService::CreateFixedFromPacResult("QUIC myproxy:70"));
 
@@ -443,6 +444,7 @@ TEST_P(QuicNetworkTransactionTest, QuicProxy) {
   CreateSession();
 
   SendRequestAndExpectQuicResponseFromProxy("hello!");
+  params_.enable_quic_for_proxies = false;
 }
 
 TEST_P(QuicNetworkTransactionTest, ForceQuicWithErrorConnecting) {