Create WebSocketTransportClientSocketPool

net/socket/websocket_transport_client_socket_pool_unittest.cc

+// Copyright 2014 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/socket/websocket_transport_client_socket_pool.h"
+
+#include <queue>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/strings/stringprintf.h"
+#include "base/time/time.h"
+#include "net/base/capturing_net_log.h"
+#include "net/base/ip_endpoint.h"
+#include "net/base/load_timing_info.h"
+#include "net/base/load_timing_info_test_util.h"
+#include "net/base/net_errors.h"
+#include "net/base/net_util.h"
+#include "net/base/test_completion_callback.h"
+#include "net/dns/mock_host_resolver.h"
+#include "net/socket/client_socket_handle.h"
+#include "net/socket/client_socket_pool_histograms.h"
+#include "net/socket/socket_test_util.h"
+#include "net/socket/stream_socket.h"
+#include "net/socket/transport_client_socket_pool_test_util.h"
+#include "net/socket/websocket_endpoint_lock_manager.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+namespace {
+
+const int kMaxSockets = 32;
+const int kMaxSocketsPerGroup = 6;
+const net::RequestPriority kDefaultPriority = LOW;
+
+// RunLoop doesn't support this natively but it is easy to emulate.
+void RunLoopForTimePeriod(base::TimeDelta period) {
+  base::RunLoop run_loop;
+  base::Closure quit_closure(run_loop.QuitClosure());
+  base::MessageLoop::current()->PostDelayedTask(
+      FROM_HERE, quit_closure, period);
+  run_loop.Run();
+}
+
+class WebSocketTransportClientSocketPoolTest : public testing::Test {
+ protected:
+  WebSocketTransportClientSocketPoolTest()
+      : params_(new TransportSocketParams(HostPortPair("www.google.com", 80),
+                                          false,
+                                          false,
+                                          OnHostResolutionCallback())),
+        histograms_(new ClientSocketPoolHistograms("TCPUnitTest")),
+        host_resolver_(new MockHostResolver),
+        client_socket_factory_(&net_log_),
+        pool_(kMaxSockets,
+              kMaxSocketsPerGroup,
+              histograms_.get(),
+              host_resolver_.get(),
+              &client_socket_factory_,
+              NULL) {}
+
+  virtual ~WebSocketTransportClientSocketPoolTest() {
+    ReleaseAllConnections(ClientSocketPoolTest::NO_KEEP_ALIVE);
+    EXPECT_TRUE(WebSocketEndpointLockManager::GetInstance()->IsEmpty());
+  }
+
+  int StartRequest(const std::string& group_name, RequestPriority priority) {
+    scoped_refptr<TransportSocketParams> params(
+        new TransportSocketParams(HostPortPair("www.google.com", 80),
+                                  false,
+                                  false,
+                                  OnHostResolutionCallback()));
+    return test_base_.StartRequestUsingPool(
+        &pool_, group_name, priority, params);
+  }
+
+  int GetOrderOfRequest(size_t index) {
+    return test_base_.GetOrderOfRequest(index);
+  }
+
+  bool ReleaseOneConnection(ClientSocketPoolTest::KeepAlive keep_alive) {
+    return test_base_.ReleaseOneConnection(keep_alive);
+  }
+
+  void ReleaseAllConnections(ClientSocketPoolTest::KeepAlive keep_alive) {
+    test_base_.ReleaseAllConnections(keep_alive);
+  }
+
+  TestSocketRequest* request(int i) { return test_base_.request(i); }
+
+  ScopedVector<TestSocketRequest>* requests() { return test_base_.requests(); }
+  size_t completion_count() const { return test_base_.completion_count(); }
+
+  CapturingNetLog net_log_;
+  scoped_refptr<TransportSocketParams> params_;
+  scoped_ptr<ClientSocketPoolHistograms> histograms_;
+  scoped_ptr<MockHostResolver> host_resolver_;
+  MockTransportClientSocketFactory client_socket_factory_;
+  WebSocketTransportClientSocketPool pool_;
+  ClientSocketPoolTest test_base_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WebSocketTransportClientSocketPoolTest);
+};
+
+TEST_F(WebSocketTransportClientSocketPoolTest, Basic) {
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv = handle.Init(
+      "a", params_, LOW, callback.callback(), &pool_, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(handle.is_initialized());
+  EXPECT_FALSE(handle.socket());
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_TRUE(handle.is_initialized());
+  EXPECT_TRUE(handle.socket());
+  TestLoadTimingInfoConnectedNotReused(handle);
+}
+
+// Make sure that WebSocketTransportConnectJob passes on its priority to its
+// HostResolver request on Init.
+TEST_F(WebSocketTransportClientSocketPoolTest, SetResolvePriorityOnInit) {
+  for (int i = MINIMUM_PRIORITY; i <= MAXIMUM_PRIORITY; ++i) {
+    RequestPriority priority = static_cast<RequestPriority>(i);
+    TestCompletionCallback callback;
+    ClientSocketHandle handle;
+    EXPECT_EQ(ERR_IO_PENDING,
+              handle.Init("a",
+                          params_,
+                          priority,
+                          callback.callback(),
+                          &pool_,
+                          BoundNetLog()));
+    EXPECT_EQ(priority, host_resolver_->last_request_priority());
+  }
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, InitHostResolutionFailure) {
+  host_resolver_->rules()->AddSimulatedFailure("unresolvable.host.name");
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  HostPortPair host_port_pair("unresolvable.host.name", 80);
+  scoped_refptr<TransportSocketParams> dest(new TransportSocketParams(
+      host_port_pair, false, false, OnHostResolutionCallback()));
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle.Init("a",
+                        dest,
+                        kDefaultPriority,
+                        callback.callback(),
+                        &pool_,
+                        BoundNetLog()));
+  EXPECT_EQ(ERR_NAME_NOT_RESOLVED, callback.WaitForResult());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, InitConnectionFailure) {
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_FAILING_CLIENT_SOCKET);
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle.Init("a",
+                        params_,
+                        kDefaultPriority,
+                        callback.callback(),
+                        &pool_,
+                        BoundNetLog()));
+  EXPECT_EQ(ERR_CONNECTION_FAILED, callback.WaitForResult());
+
+  // Make the host resolutions complete synchronously this time.
+  host_resolver_->set_synchronous_mode(true);
+  EXPECT_EQ(ERR_CONNECTION_FAILED,
+            handle.Init("a",
+                        params_,
+                        kDefaultPriority,
+                        callback.callback(),
+                        &pool_,
+                        BoundNetLog()));
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, PendingRequestsFinishFifo) {
+  // First request finishes asynchronously.
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+
+  // Make all subsequent host resolutions complete synchronously.
+  host_resolver_->set_synchronous_mode(true);
+
+  // Rest of them wait for the first socket to be released.
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+
+  ReleaseAllConnections(ClientSocketPoolTest::KEEP_ALIVE);
+
+  EXPECT_EQ(6, client_socket_factory_.allocation_count());
+
+  // One initial asynchronous request and then 5 pending requests.
+  EXPECT_EQ(6U, completion_count());
+
+  // The requests finish in FIFO order.
+  EXPECT_EQ(1, GetOrderOfRequest(1));
+  EXPECT_EQ(2, GetOrderOfRequest(2));
+  EXPECT_EQ(3, GetOrderOfRequest(3));
+  EXPECT_EQ(4, GetOrderOfRequest(4));
+  EXPECT_EQ(5, GetOrderOfRequest(5));
+  EXPECT_EQ(6, GetOrderOfRequest(6));
+
+  // Make sure we test order of all requests made.
+  EXPECT_EQ(ClientSocketPoolTest::kIndexOutOfBounds, GetOrderOfRequest(7));
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, PendingRequests_NoKeepAlive) {
+  // First request finishes asynchronously.
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+
+  // Make all subsequent host resolutions complete synchronously.
+  host_resolver_->set_synchronous_mode(true);
+
+  // Rest of them wait foe the first socket to be released.

[tyoshino (SeeGerritForStatus), 2014/06/24 05:46:52]

foe -> for

[Adam Rice, 2014/06/24 06:28:37]

Done.

+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+
+  ReleaseAllConnections(ClientSocketPoolTest::NO_KEEP_ALIVE);
+
+  // The pending requests should finish successfully.
+  EXPECT_EQ(OK, request(1)->WaitForResult());
+  EXPECT_EQ(OK, request(2)->WaitForResult());
+  EXPECT_EQ(OK, request(3)->WaitForResult());
+  EXPECT_EQ(OK, request(4)->WaitForResult());
+  EXPECT_EQ(OK, request(5)->WaitForResult());
+
+  EXPECT_EQ(static_cast<int>(requests()->size()),
+            client_socket_factory_.allocation_count());
+
+  // First asynchronous request, and then last 5 pending requests.
+  EXPECT_EQ(6U, completion_count());
+}
+
+// This test will start up a RequestSocket() and then immediately Cancel() it.
+// The pending host resolution will eventually complete, and destroy the
+// ClientSocketPool which will crash if the group was not cleared properly.
+TEST_F(WebSocketTransportClientSocketPoolTest, CancelRequestClearGroup) {
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle.Init("a",
+                        params_,
+                        kDefaultPriority,
+                        callback.callback(),
+                        &pool_,
+                        BoundNetLog()));
+  handle.Reset();
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, TwoRequestsCancelOne) {
+  ClientSocketHandle handle;
+  TestCompletionCallback callback;
+  ClientSocketHandle handle2;
+  TestCompletionCallback callback2;
+
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle.Init("a",
+                        params_,
+                        kDefaultPriority,
+                        callback.callback(),
+                        &pool_,
+                        BoundNetLog()));
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle2.Init("a",
+                         params_,
+                         kDefaultPriority,
+                         callback2.callback(),
+                         &pool_,
+                         BoundNetLog()));
+
+  handle.Reset();
+
+  EXPECT_EQ(OK, callback2.WaitForResult());
+  handle2.Reset();
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, ConnectCancelConnect) {
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_PENDING_CLIENT_SOCKET);
+  ClientSocketHandle handle;
+  TestCompletionCallback callback;
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle.Init("a",
+                        params_,
+                        kDefaultPriority,
+                        callback.callback(),
+                        &pool_,
+                        BoundNetLog()));
+
+  handle.Reset();
+
+  TestCompletionCallback callback2;
+  EXPECT_EQ(ERR_IO_PENDING,
+            handle.Init("a",
+                        params_,
+                        kDefaultPriority,
+                        callback2.callback(),
+                        &pool_,
+                        BoundNetLog()));
+
+  host_resolver_->set_synchronous_mode(true);
+  // At this point, handle has two ConnectingSockets out for it.  Due to the
+  // setting the mock resolver into synchronous mode, the host resolution for
+  // both will return in the same loop of the MessageLoop.  The client socket
+  // is a pending socket, so the Connect() will asynchronously complete on the
+  // next loop of the MessageLoop.  That means that the first
+  // ConnectingSocket will enter OnIOComplete, and then the second one will.
+  // If the first one is not cancelled, it will advance the load state, and
+  // then the second one will crash.
+
+  EXPECT_EQ(OK, callback2.WaitForResult());
+  EXPECT_FALSE(callback.have_result());
+
+  handle.Reset();
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, CancelRequest) {
+  // First request finishes asynchronously.
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+
+  // Make all subsequent host resolutions complete synchronously.
+  host_resolver_->set_synchronous_mode(true);
+
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+
+  // Cancel a request.
+  const size_t index_to_cancel = 2;
+  EXPECT_FALSE(request(index_to_cancel)->handle()->is_initialized());
+  request(index_to_cancel)->handle()->Reset();
+
+  ReleaseAllConnections(ClientSocketPoolTest::KEEP_ALIVE);
+
+  EXPECT_EQ(5, client_socket_factory_.allocation_count());
+
+  EXPECT_EQ(1, GetOrderOfRequest(1));
+  EXPECT_EQ(2, GetOrderOfRequest(2));
+  EXPECT_EQ(ClientSocketPoolTest::kRequestNotFound,
+            GetOrderOfRequest(3));  // Canceled request.
+  EXPECT_EQ(3, GetOrderOfRequest(4));
+  EXPECT_EQ(4, GetOrderOfRequest(5));
+  EXPECT_EQ(5, GetOrderOfRequest(6));
+
+  // Make sure we test order of all requests made.
+  EXPECT_EQ(ClientSocketPoolTest::kIndexOutOfBounds, GetOrderOfRequest(7));
+}
+
+class RequestSocketCallback : public TestCompletionCallbackBase {
+ public:
+  RequestSocketCallback(ClientSocketHandle* handle,
+                        WebSocketTransportClientSocketPool* pool)
+      : handle_(handle),
+        pool_(pool),
+        within_callback_(false),
+        callback_(base::Bind(&RequestSocketCallback::OnComplete,
+                             base::Unretained(this))) {}
+
+  virtual ~RequestSocketCallback() {}
+
+  const CompletionCallback& callback() const { return callback_; }
+
+ private:
+  void OnComplete(int result) {
+    SetResult(result);
+    ASSERT_EQ(OK, result);
+
+    if (!within_callback_) {
+      // Don't allow reuse of the socket.  Disconnect it and then release it and
+      // run through the MessageLoop once to get it completely released.
+      handle_->socket()->Disconnect();
+      handle_->Reset();
+      {
+        base::MessageLoop::ScopedNestableTaskAllower allow(
+            base::MessageLoop::current());
+        base::MessageLoop::current()->RunUntilIdle();
+      }
+      within_callback_ = true;
+      scoped_refptr<TransportSocketParams> dest(
+          new TransportSocketParams(HostPortPair("www.google.com", 80),
+                                    false,
+                                    false,
+                                    OnHostResolutionCallback()));
+      int rv =
+          handle_->Init("a", dest, LOWEST, callback(), pool_, BoundNetLog());
+      EXPECT_EQ(OK, rv);
+    }
+  }
+
+  ClientSocketHandle* const handle_;
+  WebSocketTransportClientSocketPool* const pool_;
+  bool within_callback_;
+  CompletionCallback callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(RequestSocketCallback);
+};
+
+TEST_F(WebSocketTransportClientSocketPoolTest, RequestTwice) {
+  ClientSocketHandle handle;
+  RequestSocketCallback callback(&handle, &pool_);
+  scoped_refptr<TransportSocketParams> dest(
+      new TransportSocketParams(HostPortPair("www.google.com", 80),
+                                false,
+                                false,
+                                OnHostResolutionCallback()));
+  int rv = handle.Init(
+      "a", dest, LOWEST, callback.callback(), &pool_, BoundNetLog());
+  ASSERT_EQ(ERR_IO_PENDING, rv);
+
+  // The callback is going to request "www.google.com". We want it to complete
+  // synchronously this time.
+  host_resolver_->set_synchronous_mode(true);
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+
+  handle.Reset();
+}
+
+// Make sure that pending requests get serviced after active requests get
+// cancelled.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       CancelActiveRequestWithPendingRequests) {
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_PENDING_CLIENT_SOCKET);
+
+  // Queue up all the requests
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+
+  // Now, kMaxSocketsPerGroup requests should be active.  Let's cancel them.
+  ASSERT_LE(kMaxSocketsPerGroup, static_cast<int>(requests()->size()));
+  for (int i = 0; i < kMaxSocketsPerGroup; i++)
+    request(i)->handle()->Reset();
+
+  // Let's wait for the rest to complete now.
+  for (size_t i = kMaxSocketsPerGroup; i < requests()->size(); ++i) {
+    EXPECT_EQ(OK, request(i)->WaitForResult());
+    request(i)->handle()->Reset();
+  }
+
+  EXPECT_EQ(requests()->size() - kMaxSocketsPerGroup, completion_count());
+}
+
+// Make sure that pending requests get serviced after active requests fail.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       FailingActiveRequestWithPendingRequests) {
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_PENDING_FAILING_CLIENT_SOCKET);
+
+  const int kNumRequests = 2 * kMaxSocketsPerGroup + 1;
+  ASSERT_LE(kNumRequests, kMaxSockets);  // Otherwise the test will hang.
+
+  // Queue up all the requests
+  for (int i = 0; i < kNumRequests; i++)
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+
+  for (int i = 0; i < kNumRequests; i++)
+    EXPECT_EQ(ERR_CONNECTION_FAILED, request(i)->WaitForResult());
+}
+
+// The lock on the endpoint is released when a ClientSocketHandle is reset.
+TEST_F(WebSocketTransportClientSocketPoolTest, LockReleasedOnHandleReset) {
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+  EXPECT_FALSE(request(1)->handle()->is_initialized());
+  request(0)->handle()->Reset();
+  base::RunLoop().RunUntilIdle();
+  EXPECT_TRUE(request(1)->handle()->is_initialized());
+}
+
+// The lock on the endpoint is released when a ClientSocketHandle is deleted.
+TEST_F(WebSocketTransportClientSocketPoolTest, LockReleasedOnHandleDelete) {
+  TestCompletionCallback callback;
+  scoped_ptr<ClientSocketHandle> handle(new ClientSocketHandle);
+  int rv = handle->Init(
+      "a", params_, LOW, callback.callback(), &pool_, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_FALSE(request(0)->handle()->is_initialized());
+  handle.reset();
+  base::RunLoop().RunUntilIdle();
+  EXPECT_TRUE(request(0)->handle()->is_initialized());
+}
+
+// A new connection is performed when the lock on the previous connection is
+// explicity released.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       ConnectionProceedsOnExplicitRelease) {
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+  EXPECT_FALSE(request(1)->handle()->is_initialized());
+  WebSocketTransportClientSocketPool::UnlockEndpoint(request(0)->handle());
+  base::RunLoop().RunUntilIdle();
+  EXPECT_TRUE(request(1)->handle()->is_initialized());
+}
+
+// A connection which is cancelled before completion does not block subsequent
+// connections.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       CancelDuringConnectionReleasesLock) {
+  MockTransportClientSocketFactory::ClientSocketType case_types[] = {
+      MockTransportClientSocketFactory::MOCK_STALLED_CLIENT_SOCKET,
+      MockTransportClientSocketFactory::MOCK_PENDING_CLIENT_SOCKET};
+
+  client_socket_factory_.set_client_socket_types(case_types,
+                                                 arraysize(case_types));
+
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  base::RunLoop().RunUntilIdle();
+  pool_.CancelRequest("a", (request(0))->handle());
+  EXPECT_EQ(OK, request(1)->WaitForResult());
+}
+
+// Test the case of the IPv6 address stalling, and falling back to the IPv4
+// socket which finishes first.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       IPv6FallbackSocketIPv4FinishesFirst) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  MockTransportClientSocketFactory::ClientSocketType case_types[] = {
+      // This is the IPv6 socket.
+      MockTransportClientSocketFactory::MOCK_STALLED_CLIENT_SOCKET,
+      // This is the IPv4 socket.
+      MockTransportClientSocketFactory::MOCK_PENDING_CLIENT_SOCKET};
+
+  client_socket_factory_.set_client_socket_types(case_types, 2);
+
+  // Resolve an AddressList with a IPv6 address first and then a IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule(
+      "*", "2:abcd::3:4:ff,2.2.2.2", std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(handle.is_initialized());
+  EXPECT_FALSE(handle.socket());
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_TRUE(handle.is_initialized());
+  EXPECT_TRUE(handle.socket());
+  IPEndPoint endpoint;
+  handle.socket()->GetLocalAddress(&endpoint);
+  EXPECT_EQ(kIPv4AddressSize, endpoint.address().size());
+  EXPECT_EQ(2, client_socket_factory_.allocation_count());
+}
+
+// Test the case of the IPv6 address being slow, thus falling back to trying to
+// connect to the IPv4 address, but having the connect to the IPv6 address
+// finish first.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       IPv6FallbackSocketIPv6FinishesFirst) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  MockTransportClientSocketFactory::ClientSocketType case_types[] = {
+      // This is the IPv6 socket.
+      MockTransportClientSocketFactory::MOCK_DELAYED_CLIENT_SOCKET,
+      // This is the IPv4 socket.
+      MockTransportClientSocketFactory::MOCK_STALLED_CLIENT_SOCKET};
+
+  client_socket_factory_.set_client_socket_types(case_types, 2);
+  client_socket_factory_.set_delay(base::TimeDelta::FromMilliseconds(
+      TransportConnectJobHelper::kIPv6FallbackTimerInMs + 50));
+
+  // Resolve an AddressList with a IPv6 address first and then a IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule(
+      "*", "2:abcd::3:4:ff,2.2.2.2", std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(handle.is_initialized());
+  EXPECT_FALSE(handle.socket());
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_TRUE(handle.is_initialized());
+  EXPECT_TRUE(handle.socket());
+  IPEndPoint endpoint;
+  handle.socket()->GetLocalAddress(&endpoint);
+  EXPECT_EQ(kIPv6AddressSize, endpoint.address().size());
+  EXPECT_EQ(2, client_socket_factory_.allocation_count());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       IPv6NoIPv4AddressesToFallbackTo) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_DELAYED_CLIENT_SOCKET);
+
+  // Resolve an AddressList with only IPv6 addresses.
+  host_resolver_->rules()->AddIPLiteralRule(
+      "*", "2:abcd::3:4:ff,3:abcd::3:4:ff", std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(handle.is_initialized());
+  EXPECT_FALSE(handle.socket());
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_TRUE(handle.is_initialized());
+  EXPECT_TRUE(handle.socket());
+  IPEndPoint endpoint;
+  handle.socket()->GetLocalAddress(&endpoint);
+  EXPECT_EQ(kIPv6AddressSize, endpoint.address().size());
+  EXPECT_EQ(1, client_socket_factory_.allocation_count());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, IPv4HasNoFallback) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_DELAYED_CLIENT_SOCKET);
+
+  // Resolve an AddressList with only IPv4 addresses.
+  host_resolver_->rules()->AddIPLiteralRule("*", "1.1.1.1", std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(handle.is_initialized());
+  EXPECT_FALSE(handle.socket());
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_TRUE(handle.is_initialized());
+  EXPECT_TRUE(handle.socket());
+  IPEndPoint endpoint;
+  handle.socket()->GetLocalAddress(&endpoint);
+  EXPECT_EQ(kIPv4AddressSize, endpoint.address().size());
+  EXPECT_EQ(1, client_socket_factory_.allocation_count());
+}
+
+// If all IPv6 addresses fail to connect synchronously, then IPv4 connections
+// proceeed immediately.
+TEST_F(WebSocketTransportClientSocketPoolTest, IPv6InstantFail) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  MockTransportClientSocketFactory::ClientSocketType case_types[] = {
+      // First IPv6 socket.
+      MockTransportClientSocketFactory::MOCK_FAILING_CLIENT_SOCKET,
+      // Second IPv6 socket.
+      MockTransportClientSocketFactory::MOCK_FAILING_CLIENT_SOCKET,
+      // This is the IPv4 socket.
+      MockTransportClientSocketFactory::MOCK_CLIENT_SOCKET};
+
+  client_socket_factory_.set_client_socket_types(case_types,
+                                                 arraysize(case_types));
+
+  // Resolve an AddressList with two IPv6 addresses and then a IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule(
+      "*", "2:abcd::3:4:ff,2:abcd::3:5:ff,2.2.2.2", std::string());
+  host_resolver_->set_synchronous_mode(true);
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(OK, rv);
+  ASSERT_TRUE(handle.socket());
+
+  IPEndPoint endpoint;
+  handle.socket()->GetPeerAddress(&endpoint);
+  EXPECT_EQ("2.2.2.2", endpoint.ToStringWithoutPort());
+}
+
+// If all IPv6 addresses fail before the IPv4 fallback timeout, then the IPv4
+// connections proceed immediately.
+TEST_F(WebSocketTransportClientSocketPoolTest, IPv6RapidFail) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  MockTransportClientSocketFactory::ClientSocketType case_types[] = {
+      // First IPv6 socket.
+      MockTransportClientSocketFactory::MOCK_PENDING_FAILING_CLIENT_SOCKET,
+      // Second IPv6 socket.
+      MockTransportClientSocketFactory::MOCK_PENDING_FAILING_CLIENT_SOCKET,
+      // This is the IPv4 socket.
+      MockTransportClientSocketFactory::MOCK_CLIENT_SOCKET};
+
+  client_socket_factory_.set_client_socket_types(case_types,
+                                                 arraysize(case_types));
+
+  // Resolve an AddressList with two IPv6 addresses and then a IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule(
+      "*", "2:abcd::3:4:ff,2:abcd::3:5:ff,2.2.2.2", std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  EXPECT_FALSE(handle.socket());
+
+  base::Time start(base::Time::NowFromSystemTime());
+  EXPECT_EQ(OK, callback.WaitForResult());
+  EXPECT_LT(base::Time::NowFromSystemTime() - start,
+            base::TimeDelta::FromMilliseconds(
+                TransportConnectJobHelper::kIPv6FallbackTimerInMs));
+  ASSERT_TRUE(handle.socket());
+
+  IPEndPoint endpoint;
+  handle.socket()->GetPeerAddress(&endpoint);
+  EXPECT_EQ("2.2.2.2", endpoint.ToStringWithoutPort());
+}
+
+// If two sockets connect successfully, the one which connected first wins (this
+// can only happen if the sockets are different types, since sockets of the same
+// type do not race).
+TEST_F(WebSocketTransportClientSocketPoolTest, FirstSuccessWins) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_TRIGGERABLE_CLIENT_SOCKET);
+
+  // Resolve an AddressList with an IPv6 addresses and an IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule(
+      "*", "2:abcd::3:4:ff,2.2.2.2", std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  ASSERT_FALSE(handle.socket());
+
+  base::Closure ipv6_connect_trigger =
+      client_socket_factory_.WaitForTriggerableSocketCreation();
+  base::Closure ipv4_connect_trigger =
+      client_socket_factory_.WaitForTriggerableSocketCreation();
+
+  ipv4_connect_trigger.Run();
+  ipv6_connect_trigger.Run();
+
+  EXPECT_EQ(OK, callback.WaitForResult());
+  ASSERT_TRUE(handle.socket());
+
+  IPEndPoint endpoint;
+  handle.socket()->GetPeerAddress(&endpoint);
+  EXPECT_EQ("2.2.2.2", endpoint.ToStringWithoutPort());
+}
+
+// We should not report failure until all connections have failed.
+TEST_F(WebSocketTransportClientSocketPoolTest, LastFailureWins) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_DELAYED_FAILING_CLIENT_SOCKET);
+  base::TimeDelta delay = base::TimeDelta::FromMilliseconds(
+      TransportConnectJobHelper::kIPv6FallbackTimerInMs / 3);
+  client_socket_factory_.set_delay(delay);
+
+  // Resolve an AddressList with 4 IPv6 addresses and 2 IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule("*",
+                                            "1:abcd::3:4:ff,2:abcd::3:4:ff,"
+                                            "3:abcd::3:4:ff,4:abcd::3:4:ff,"
+                                            "1.1.1.1,2.2.2.2",
+                                            std::string());
+
+  // Expected order of events:
+  // After 100ms: Connect to 1:abcd::3:4:ff times out
+  // After 200ms: Connect to 2:abcd::3:4:ff times out
+  // After 300ms: Connect to 3:abcd::3:4:ff times out, IPv4 fallback starts
+  // After 400ms: Connect to 4:abcd::3:4:ff and 1.1.1.1 time out
+  // After 500ms: Connect to 2.2.2.2 times out
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+  base::Time start(base::Time::NowFromSystemTime());
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+
+  EXPECT_EQ(ERR_CONNECTION_FAILED, callback.WaitForResult());
+
+  EXPECT_GE(base::Time::NowFromSystemTime() - start, delay * 5);
+}
+
+// Global timeout for all connects applies. This test is disabled by default
+// because it takes 4 minutes. Run with --gtest_also_run_disabled_tests if you
+// want to run it.
+TEST_F(WebSocketTransportClientSocketPoolTest, DISABLED_OverallTimeoutApplies) {
+  WebSocketTransportClientSocketPool pool(kMaxSockets,
+                                          kMaxSocketsPerGroup,
+                                          histograms_.get(),
+                                          host_resolver_.get(),
+                                          &client_socket_factory_,
+                                          NULL);
+  const base::TimeDelta connect_job_timeout = pool.ConnectionTimeout();
+
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_DELAYED_FAILING_CLIENT_SOCKET);
+  client_socket_factory_.set_delay(base::TimeDelta::FromSeconds(1) +
+                                   connect_job_timeout / 6);
+
+  // Resolve an AddressList with 6 IPv6 addresses and 6 IPv4 address.
+  host_resolver_->rules()->AddIPLiteralRule("*",
+                                            "1:abcd::3:4:ff,2:abcd::3:4:ff,"
+                                            "3:abcd::3:4:ff,4:abcd::3:4:ff,"
+                                            "5:abcd::3:4:ff,6:abcd::3:4:ff,"
+                                            "1.1.1.1,2.2.2.2,3.3.3.3,"
+                                            "4.4.4.4,5.5.5.5,6.6.6.6",
+                                            std::string());
+
+  TestCompletionCallback callback;
+  ClientSocketHandle handle;
+
+  int rv =
+      handle.Init("a", params_, LOW, callback.callback(), &pool, BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+
+  EXPECT_EQ(ERR_TIMED_OUT, callback.WaitForResult());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, MaxSocketsEnforced) {
+  host_resolver_->set_synchronous_mode(true);
+  for (int i = 0; i < kMaxSockets; ++i) {
+    EXPECT_EQ(OK, StartRequest("a", kDefaultPriority));
+    WebSocketTransportClientSocketPool::UnlockEndpoint(request(i)->handle());
+  }
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, MaxSocketsEnforcedWhenPending) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  // Now there are 32 sockets waiting to connect, and one stalled.
+  for (int i = 0; i < kMaxSockets; ++i) {
+    base::RunLoop().RunUntilIdle();
+    EXPECT_TRUE(request(i)->handle()->is_initialized());
+    EXPECT_TRUE(request(i)->handle()->socket());
+    WebSocketTransportClientSocketPool::UnlockEndpoint(request(i)->handle());
+  }
+  // Now there are 32 sockets connected, and one stalled.
+  base::RunLoop().RunUntilIdle();
+  EXPECT_FALSE(request(kMaxSockets)->handle()->is_initialized());
+  EXPECT_FALSE(request(kMaxSockets)->handle()->socket());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, StalledSocketReleased) {
+  host_resolver_->set_synchronous_mode(true);
+  for (int i = 0; i < kMaxSockets; ++i) {
+    EXPECT_EQ(OK, StartRequest("a", kDefaultPriority));
+    WebSocketTransportClientSocketPool::UnlockEndpoint(request(i)->handle());
+  }
+
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  ReleaseOneConnection(ClientSocketPoolTest::NO_KEEP_ALIVE);
+  EXPECT_TRUE(request(kMaxSockets)->handle()->is_initialized());
+  EXPECT_TRUE(request(kMaxSockets)->handle()->socket());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest, IsStalledTrueWhenStalled) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+  EXPECT_TRUE(pool_.IsStalled());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       CancellingPendingSocketUnstallsStalledSocket) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  EXPECT_EQ(OK, request(0)->WaitForResult());
+  request(1)->handle()->Reset();
+  base::RunLoop().RunUntilIdle();
+  EXPECT_FALSE(pool_.IsStalled());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       LoadStateOfStalledSocketIsWaitingForAvailableSocket) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  EXPECT_EQ(LOAD_STATE_WAITING_FOR_AVAILABLE_SOCKET,
+            pool_.GetLoadState("a", request(kMaxSockets)->handle()));
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       CancellingStalledSocketUnstallsPool) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  request(kMaxSockets)->handle()->Reset();
+  EXPECT_FALSE(pool_.IsStalled());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       FlushWithErrorFlushesPendingConnections) {
+  EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  pool_.FlushWithError(ERR_FAILED);
+  EXPECT_EQ(ERR_FAILED, request(0)->WaitForResult());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       FlushWithErrorFlushesStalledConnections) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  pool_.FlushWithError(ERR_FAILED);
+  EXPECT_EQ(ERR_FAILED, request(kMaxSockets)->WaitForResult());
+}
+
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       AfterFlushWithErrorCanMakeNewConnections) {
+  for (int i = 0; i < kMaxSockets + 1; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  pool_.FlushWithError(ERR_FAILED);
+  host_resolver_->set_synchronous_mode(true);
+  EXPECT_EQ(OK, StartRequest("a", kDefaultPriority));
+}
+
+// Deleting pending connections can release the lock on the endpoint, which can
+// in principle lead to other pending connections succeeding. However, when we
+// call FlushWithError(), everything should fail.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       FlushWithErrorDoesNotCauseSuccessfulConnections) {
+  host_resolver_->set_synchronous_mode(true);
+  MockTransportClientSocketFactory::ClientSocketType first_type[] = {
+    // First socket
+    MockTransportClientSocketFactory::MOCK_PENDING_CLIENT_SOCKET
+  };
+  client_socket_factory_.set_client_socket_types(first_type,
+                                                 arraysize(first_type));
+  // The rest of the sockets will connect synchronously.
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_CLIENT_SOCKET);
+  for (int i = 0; i < kMaxSockets; ++i) {
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  // Now we have one socket in STATE_TRANSPORT_CONNECT and the rest in
+  // STATE_OBTAIN_LOCK. If any of the sockets in STATE_OBTAIN_LOCK is given the
+  // lock, they will synchronously connect.
+  pool_.FlushWithError(ERR_FAILED);
+  for (int i = 0; i < kMaxSockets; ++i) {
+    EXPECT_EQ(ERR_FAILED, request(i)->WaitForResult());
+  }
+}
+
+// This is a regression test for the first attempted fix for
+// FlushWithErrorDoesNotCauseSuccessfulConnections. Because a ConnectJob can
+// have both IPv4 and IPv6 subjobs, it can be both connecting and waiting for
+// the lock at the same time.
+TEST_F(WebSocketTransportClientSocketPoolTest,
+       FlushWithErrorDoesNotCauseSuccessfulConnectionsMultipleAddressTypes) {
+  host_resolver_->set_synchronous_mode(true);
+  // The first |kMaxSockets| sockets to connect will be IPv6. Then we will have
+  // one IPv4.
+  std::vector<MockTransportClientSocketFactory::ClientSocketType> socket_types(
+      kMaxSockets + 1,
+      MockTransportClientSocketFactory::MOCK_STALLED_CLIENT_SOCKET);
+  client_socket_factory_.set_client_socket_types(&socket_types[0],
+                                                 socket_types.size());
+  // The rest of the sockets will connect synchronously.
+  client_socket_factory_.set_client_socket_type(
+      MockTransportClientSocketFactory::MOCK_CLIENT_SOCKET);
+  for (int i = 0; i < kMaxSockets; ++i) {
+    host_resolver_->rules()->ClearRules();
+    // Each connect job has a different IPv6 address but the same IPv4 address.
+    // So the IPv6 connections happen in parallel but the IPv4 ones are
+    // serialised.
+    host_resolver_->rules()->AddIPLiteralRule("*",
+                                              base::StringPrintf(
+                                                  "%x:abcd::3:4:ff,"
+                                                  "1.1.1.1",
+                                                  i + 1),
+                                              std::string());
+    EXPECT_EQ(ERR_IO_PENDING, StartRequest("a", kDefaultPriority));
+  }
+  // Now we have |kMaxSockets| IPv6 sockets stalled in connect. No IPv4 sockets
+  // are started yet.
+  RunLoopForTimePeriod(base::TimeDelta::FromMilliseconds(
+      TransportConnectJobHelper::kIPv6FallbackTimerInMs));
+  // Now we have |kMaxSockets| IPv6 sockets and one IPv4 socket stalled in
+  // connect, and |kMaxSockets - 1| IPv4 sockets waiting for the endpoint lock.
+  pool_.FlushWithError(ERR_FAILED);
+  for (int i = 0; i < kMaxSockets; ++i) {
+    EXPECT_EQ(ERR_FAILED, request(i)->WaitForResult());
+  }
+}
+
+}  // namespace
+
+}  // namespace net