Added DISABLE_ALTERNATE_PROTOCOLS load flag, and use it for DRP probe.

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..de97a525d135cb282e8e7e2b3e1c03ac8e511b6b 100644
--- a/net/quic/quic_network_transaction_unittest.cc
+++ b/net/quic/quic_network_transaction_unittest.cc
@@ -9,6 +9,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
 #include "net/base/capturing_net_log.h"
+#include "net/base/load_flags.h"
 #include "net/base/net_log_unittest.h"
 #include "net/base/test_completion_callback.h"
 #include "net/cert/mock_cert_verifier.h"
@@ -583,6 +584,33 @@ TEST_P(QuicNetworkTransactionTest, DontUseAlternateProtocolProbabilityForQuic) {
 }
 
 TEST_P(QuicNetworkTransactionTest,
+       DontUseAlternateProtocolForQuicWithDisableAlternateProtocols) {
+  MockRead http_reads[] = {
+    MockRead("HTTP/1.1 200 OK\r\n"),
+    MockRead(kQuicAlternateProtocol50pctHttpHeader),
+    MockRead("hello world"),
+    MockRead(SYNCHRONOUS, ERR_TEST_PEER_CLOSE_AFTER_NEXT_MOCK_READ),
+    MockRead(ASYNC, OK)
+  };
+
+  StaticSocketDataProvider http_data(http_reads, arraysize(http_reads),
+                                     nullptr, 0);
+  socket_factory_.AddSocketDataProvider(&http_data);
+  socket_factory_.AddSocketDataProvider(&http_data);
+
+  request_.load_flags = LOAD_DISABLE_ALTERNATE_PROTOCOLS;
+
+  // Even though the alternate protocol probability works out in favor of using
+  // QUIC here, the LOAD_DISABLE_ALTERNATE_PROTOCOLS load flag should prevent
+  // QUIC from being used.
+  params_.alternate_protocol_probability_threshold = .25;
+  CreateSessionWithNextProtos();
+
+  SendRequestAndExpectHttpResponse("hello world");
+  SendRequestAndExpectHttpResponse("hello world");

[Ryan Hamilton, 2015/02/13 19:44:28]

Please add a comment about why this line is duplicated, since the duplication is
critical.

+}
+
+TEST_P(QuicNetworkTransactionTest,
        DontUseAlternateProtocolWithBadProbabilityForQuic) {
   MockRead http_reads[] = {
     MockRead("HTTP/1.1 200 OK\r\n"),