Avoid doing concurrent DNS resolves of the same hostname

net/http/http_network_layer_unittest.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/ref_counted.h"
 #include "net/base/host_resolver_unittest.h"
 #include "net/http/http_network_layer.h"
 #include "net/http/http_transaction_unittest.h"
 #include "net/proxy/proxy_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 class HttpNetworkLayerTest : public PlatformTest {
  public:
   HttpNetworkLayerTest()
       : host_mapper_(new net::RuleBasedHostMapper()),
         scoped_host_mapper_(host_mapper_.get()) {
     // TODO(darin): kill this exception once we have a way to test out the
     // HttpNetworkLayer class using loopback connections.
     host_mapper_->AllowDirectLookup("www.google.com");
   }
 
  private:
   scoped_refptr<net::RuleBasedHostMapper> host_mapper_;
   net::ScopedHostMapper scoped_host_mapper_;
 };
 
 TEST_F(HttpNetworkLayerTest, CreateAndDestroy) {
+  net::HostResolver host_resolver;
   scoped_ptr<net::ProxyService> proxy_service(net::ProxyService::CreateNull());
-  net::HttpNetworkLayer factory(proxy_service.get());
+  net::HttpNetworkLayer factory(&host_resolver, proxy_service.get());
 
   scoped_ptr<net::HttpTransaction> trans(factory.CreateTransaction());
 }
 
 TEST_F(HttpNetworkLayerTest, Suspend) {
+  net::HostResolver host_resolver;
   scoped_ptr<net::ProxyService> proxy_service(net::ProxyService::CreateNull());
-  net::HttpNetworkLayer factory(proxy_service.get());
+  net::HttpNetworkLayer factory(&host_resolver, proxy_service.get());
 
   scoped_ptr<net::HttpTransaction> trans(factory.CreateTransaction());
   trans.reset();
 
   factory.Suspend(true);
 
   trans.reset(factory.CreateTransaction());
   ASSERT_TRUE(trans == NULL);
 
   factory.Suspend(false);
 
   trans.reset(factory.CreateTransaction());
 }
 
 TEST_F(HttpNetworkLayerTest, GoogleGET) {
+  net::HostResolver host_resolver;
   scoped_ptr<net::ProxyService> proxy_service(net::ProxyService::CreateNull());
-  net::HttpNetworkLayer factory(proxy_service.get());
+  net::HttpNetworkLayer factory(&host_resolver, proxy_service.get());
 
   TestCompletionCallback callback;
 
   scoped_ptr<net::HttpTransaction> trans(factory.CreateTransaction());
 
   net::HttpRequestInfo request_info;
   request_info.url = GURL("http://www.google.com/");
   request_info.method = "GET";
   request_info.user_agent = "Foo/1.0";
   request_info.load_flags = net::LOAD_NORMAL;
 
   int rv = trans->Start(&request_info, &callback);
   if (rv == net::ERR_IO_PENDING)
     rv = callback.WaitForResult();
   EXPECT_EQ(net::OK, rv);
 
   std::string contents;
   rv = ReadTransaction(trans.get(), &contents);
   EXPECT_EQ(net::OK, rv);
 }