Avoid doing concurrent DNS resolves of the same hostname

net/base/tcp_client_socket_pool_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 "net/base/tcp_client_socket_pool.h"
 
 #include "base/message_loop.h"
 #include "net/base/client_socket.h"
 #include "net/base/client_socket_factory.h"
 #include "net/base/client_socket_handle.h"
@@ skipping 180 matching lines @@
  private:
   std::vector<TestSocketRequest*>* request_order_;
   TestCompletionCallback callback_;
 };
 
 int TestSocketRequest::completion_count = 0;
 
 class TCPClientSocketPoolTest : public testing::Test {
  protected:
   TCPClientSocketPoolTest()
-      : pool_(new TCPClientSocketPool(kMaxSocketsPerGroup,
+      // We disable caching here since these unit tests don't expect
+      // host resolving to be able to complete synchronously.
+      // TODO(eroman): enable caching.
+      : host_resolver_(0, 0),
+        pool_(new TCPClientSocketPool(kMaxSocketsPerGroup,
+                                      &host_resolver_,
                                       &client_socket_factory_)) {}
 
   virtual void SetUp() {
     TestSocketRequest::completion_count = 0;
   }
 
+  HostResolver host_resolver_;
   MockClientSocketFactory client_socket_factory_;
   scoped_refptr<ClientSocketPool> pool_;
   std::vector<TestSocketRequest*> request_order_;
 };
 
 TEST_F(TCPClientSocketPoolTest, Basic) {
   TestCompletionCallback callback;
   ClientSocketHandle handle(pool_.get());
   int rv = handle.Init("a", "www.google.com", 80, 0, &callback);
   EXPECT_EQ(ERR_IO_PENDING, rv);
@@ skipping 254 matching lines @@
 
   EXPECT_EQ(request_order_[arraysize(reqs) - 2],
             reqs[arraysize(reqs) - 1].get()) <<
       "The last request with priority 1 should not have been inserted "
       "earlier into the queue.";
 }
 
 }  // namespace
 
 }  // namespace net