Avoid doing concurrent DNS resolves of the same hostname

net/proxy/proxy_script_fetcher_unittest.cc

 // Copyright (c) 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 "net/proxy/proxy_script_fetcher.h"
 
 #include "base/file_path.h"
 #include "base/compiler_specific.h"
 #include "base/path_service.h"
 #include "net/base/net_util.h"
@@ skipping 12 matching lines @@
 struct FetchResult {
   int code;
   std::string bytes;
 };
 
 // A non-mock URL request which can access http:// and file:// urls.
 class RequestContext : public URLRequestContext {
  public:
   RequestContext() {
     net::ProxyConfig no_proxy;
+    host_resolver_ = new net::HostResolver;
     proxy_service_ = net::ProxyService::CreateFixed(no_proxy);
 
     http_transaction_factory_ =
-        new net::HttpCache(net::HttpNetworkLayer::CreateFactory(proxy_service_),
-                           disk_cache::CreateInMemoryCacheBackend(0));
+        new net::HttpCache(net::HttpNetworkLayer::CreateFactory(
+            host_resolver_, proxy_service_),
+            disk_cache::CreateInMemoryCacheBackend(0));
   }
   ~RequestContext() {
     delete http_transaction_factory_;
     delete proxy_service_;
+    delete host_resolver_;
   }
 };
 
 // Helper for doing synch fetches. This object lives in SynchFetcher's
 // |io_thread_| and communicates with SynchFetcher though (|result|, |event|).
 class SynchFetcherThreadHelper {
  public:
   SynchFetcherThreadHelper(base::WaitableEvent* event, FetchResult* result)
       : event_(event),
         fetch_result_(result),
@@ skipping 274 matching lines @@
 
   { // Make sure we can still fetch regular URLs.
     GURL url = server->TestServerPage("files/pac.nsproxy");
     FetchResult result = pac_fetcher.Fetch(url);
     EXPECT_EQ(net::OK, result.code);
     EXPECT_EQ("-pac.nsproxy-\n", result.bytes);
   }
 }
 
 }  // namespace net