Do not spawn a thread in browser/interactive ui tests before spawning sandbox host process

* Introduced DBThreadManager::SetInstanceForTesting to specify the instance to be used when DBThreadManager::Initialize is called in the browser setup rocess.
* Temporarily stop the thread in EmbeddedTestServer to fork/exec sandbox host process properly.

BUG=322732
TBR=sky@chromium.org

Review URL: https://codereview.chromium.org/83633004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238554 0039d316-1c4b-4281-b951-d872f2087c98

17 files changed, 119 insertions, 64 deletions

diff --git a/chrome/browser/apps/app_browsertest.cc b/chrome/browser/apps/app_browsertest.cc
index 39356b5..f2c1ab5 100644
--- a/chrome/browser/apps/app_browsertest.cc
+++ b/chrome/browser/apps/app_browsertest.cc
@@ -1235,7 +1235,7 @@ class RestartDeviceTest : public PlatformAppBrowserTest {
     power_manager_client_ = new chromeos::FakePowerManagerClient;
     dbus_manager->SetPowerManagerClient(
         scoped_ptr<chromeos::PowerManagerClient>(power_manager_client_));
-    chromeos::DBusThreadManager::InitializeForTesting(dbus_manager);
+    chromeos::DBusThreadManager::SetInstanceForTesting(dbus_manager);
   }
 
   virtual void SetUpOnMainThread() OVERRIDE {
@@ -1257,7 +1257,6 @@ class RestartDeviceTest : public PlatformAppBrowserTest {
   }
 
   virtual void TearDownInProcessBrowserTestFixture() OVERRIDE {
-    chromeos::DBusThreadManager::Shutdown();
     PlatformAppBrowserTest::TearDownInProcessBrowserTestFixture();
   }
 
diff --git a/chrome/browser/chromeos/login/crash_restore_browsertest.cc b/chrome/browser/chromeos/login/crash_restore_browsertest.cc
index ebd8f25..8bcaaf5 100644
--- a/chrome/browser/chromeos/login/crash_restore_browsertest.cc
+++ b/chrome/browser/chromeos/login/crash_restore_browsertest.cc
@@ -52,7 +52,7 @@ class CrashRestoreSimpleTest : public InProcessBrowserTest {
     session_manager_client_ = new FakeSessionManagerClient;
     dbus_thread_manager->SetSessionManagerClient(
         scoped_ptr<SessionManagerClient>(session_manager_client_));
-    DBusThreadManager::InitializeForTesting(dbus_thread_manager);
+    DBusThreadManager::SetInstanceForTesting(dbus_thread_manager);
     session_manager_client_->StartSession(kUserId1);
   }
 
diff --git a/chrome/browser/chromeos/login/kiosk_browsertest.cc b/chrome/browser/chromeos/login/kiosk_browsertest.cc
index fd11881..fd65deb 100644
--- a/chrome/browser/chromeos/login/kiosk_browsertest.cc
+++ b/chrome/browser/chromeos/login/kiosk_browsertest.cc
@@ -249,6 +249,9 @@ class KioskTest : public InProcessBrowserTest {
     embedded_test_server()->RegisterRequestHandler(
         base::Bind(&FakeGaia::HandleRequest, base::Unretained(&fake_gaia_)));
     ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
+    // Stop IO thread here because no threads are allowed while
+    // spawning sandbox host process. See crbug.com/322732.
+    embedded_test_server()->StopThread();
 
     mock_user_manager_.reset(new MockUserManager);
     AppLaunchController::SkipSplashWaitForTesting();
@@ -261,6 +264,11 @@ class KioskTest : public InProcessBrowserTest {
     host_resolver()->AddRule("*", "127.0.0.1");
   }
 
+  virtual void SetUpOnMainThread() OVERRIDE {
+    // Restart the thread as the sandbox host process has already been spawned.
+    embedded_test_server()->RestartThreadAndListen();
+  }
+
   virtual void CleanUpOnMainThread() OVERRIDE {
     // We need to clean up these objects in this specific order.
     fake_network_notifier_.reset(NULL);
@@ -801,6 +809,7 @@ class KioskEnterpriseTest : public KioskTest {
   }
 
   virtual void SetUpOnMainThread() OVERRIDE {
+    KioskTest::SetUpOnMainThread();
     // Configure kTestEnterpriseKioskApp in device policy.
     em::DeviceLocalAccountsProto* accounts =
         device_policy_test_helper_.device_policy()->payload()
@@ -832,8 +841,6 @@ class KioskEnterpriseTest : public KioskTest {
     base::RunLoop().RunUntilIdle();
     ASSERT_TRUE(token_service);
     token_service->SetAndSaveRefreshToken(kTestRefreshToken);
-
-    KioskTest::SetUpOnMainThread();
   }
 
   static void StorePolicyCallback(bool result) {
diff --git a/chrome/browser/chromeos/login/screen_locker_browsertest.cc b/chrome/browser/chromeos/login/screen_locker_browsertest.cc
index a441577..c9f721b 100644
--- a/chrome/browser/chromeos/login/screen_locker_browsertest.cc
+++ b/chrome/browser/chromeos/login/screen_locker_browsertest.cc
@@ -121,7 +121,7 @@ class ScreenLockerTest : public InProcessBrowserTest {
     fake_session_manager_client_ = new FakeSessionManagerClient;
     fake_dbus_thread_manager->SetSessionManagerClient(
         scoped_ptr<SessionManagerClient>(fake_session_manager_client_));
-    DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager);
+    DBusThreadManager::SetInstanceForTesting(fake_dbus_thread_manager);
 
     InProcessBrowserTest::SetUpInProcessBrowserTestFixture();
     zero_duration_mode_.reset(new ui::ScopedAnimationDurationScaleMode(
diff --git a/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc b/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
index e06fc9f..a77d14c 100644
--- a/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
+++ b/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
@@ -58,7 +58,7 @@ class NetworkScreenTest : public WizardInProcessBrowserTest {
     fake_session_manager_client_ = new FakeSessionManagerClient;
     fake_dbus_thread_manager->SetSessionManagerClient(
         scoped_ptr<SessionManagerClient>(fake_session_manager_client_));
-    DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager);
+    DBusThreadManager::SetInstanceForTesting(fake_dbus_thread_manager);
   }
 
   virtual void SetUpOnMainThread() OVERRIDE {
@@ -80,7 +80,6 @@ class NetworkScreenTest : public WizardInProcessBrowserTest {
 
   virtual void TearDownInProcessBrowserTestFixture() OVERRIDE {
     InProcessBrowserTest::TearDownInProcessBrowserTestFixture();
-    DBusThreadManager::Shutdown();
   }
 
   void EmulateContinueButtonExit(NetworkScreen* network_screen) {
diff --git a/chrome/browser/chromeos/login/screens/update_screen_browsertest.cc b/chrome/browser/chromeos/login/screens/update_screen_browsertest.cc
index a56d55e..b3aefe7 100644
--- a/chrome/browser/chromeos/login/screens/update_screen_browsertest.cc
+++ b/chrome/browser/chromeos/login/screens/update_screen_browsertest.cc
@@ -49,7 +49,7 @@ class UpdateScreenTest : public WizardInProcessBrowserTest {
     fake_dbus_thread_manager->SetUpdateEngineClient(
         scoped_ptr<UpdateEngineClient>(fake_update_engine_client_));
 
-    DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager);
+    DBusThreadManager::SetInstanceForTesting(fake_dbus_thread_manager);
     WizardInProcessBrowserTest::SetUpInProcessBrowserTestFixture();
 
     // Setup network portal detector to return online state for both
@@ -90,7 +90,6 @@ class UpdateScreenTest : public WizardInProcessBrowserTest {
   virtual void TearDownInProcessBrowserTestFixture() OVERRIDE {
     NetworkPortalDetector::Shutdown();
     WizardInProcessBrowserTest::TearDownInProcessBrowserTestFixture();
-    DBusThreadManager::Shutdown();
   }
 
   void SetDefaultNetworkPath(const std::string& service_path) {
diff --git a/chrome/browser/chromeos/login/wizard_controller_browsertest.cc b/chrome/browser/chromeos/login/wizard_controller_browsertest.cc
index c20afe2..6df0520 100644
--- a/chrome/browser/chromeos/login/wizard_controller_browsertest.cc
+++ b/chrome/browser/chromeos/login/wizard_controller_browsertest.cc
@@ -454,7 +454,7 @@ class WizardControllerBrokenLocalStateTest : public WizardControllerTest {
     fake_session_manager_client_ = new FakeSessionManagerClient;
     fake_dbus_thread_manager->SetSessionManagerClient(
         scoped_ptr<SessionManagerClient>(fake_session_manager_client_));
-    DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager);
+    DBusThreadManager::SetInstanceForTesting(fake_dbus_thread_manager);
   }
 
   virtual void SetUpOnMainThread() OVERRIDE {
@@ -471,7 +471,6 @@ class WizardControllerBrokenLocalStateTest : public WizardControllerTest {
 
   virtual void TearDownInProcessBrowserTestFixture() OVERRIDE {
     WizardControllerTest::TearDownInProcessBrowserTestFixture();
-    DBusThreadManager::Shutdown();
   }
 
   ErrorScreen* GetErrorScreen() {
diff --git a/chrome/browser/chromeos/policy/device_local_account_browsertest.cc b/chrome/browser/chromeos/policy/device_local_account_browsertest.cc
index a95e225..2015aab 100644
--- a/chrome/browser/chromeos/policy/device_local_account_browsertest.cc
+++ b/chrome/browser/chromeos/policy/device_local_account_browsertest.cc
@@ -74,10 +74,7 @@
 #include "chrome/common/chrome_switches.h"
 #include "chromeos/chromeos_paths.h"
 #include "chromeos/chromeos_switches.h"
-#include "chromeos/dbus/cryptohome_client.h"
-#include "chromeos/dbus/dbus_method_call_status.h"
 #include "chromeos/dbus/fake_session_manager_client.h"
-#include "chromeos/dbus/session_manager_client.h"
 #include "components/policy/core/common/external_data_fetcher.h"
 #include "components/policy/core/common/policy_map.h"
 #include "components/policy/core/common/policy_namespace.h"
@@ -101,7 +98,7 @@
 #include "net/url_request/url_request_status.h"
 #include "policy/policy_constants.h"
 #include "testing/gmock/include/gmock/gmock.h"
-#include "third_party/cros_system_api/dbus/service_constants.h"
+//#include "third_party/cros_system_api/dbus/service_constants.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "url/gurl.h"
 
@@ -296,7 +293,6 @@ class DeviceLocalAccountTest : public DevicePolicyCrosBrowserTest {
     external_data_cache_dir_override_.reset(new base::ScopedPathOverride(
         chromeos::DIR_DEVICE_LOCAL_ACCOUNT_EXTERNAL_DATA,
         external_data_cache_dir_.path()));
-
     DevicePolicyCrosBrowserTest::SetUp();
   }
 
diff --git a/chrome/browser/chromeos/policy/device_policy_cros_browser_test.cc b/chrome/browser/chromeos/policy/device_policy_cros_browser_test.cc
index eb8505c..aa617ab 100644
--- a/chrome/browser/chromeos/policy/device_policy_cros_browser_test.cc
+++ b/chrome/browser/chromeos/policy/device_policy_cros_browser_test.cc
@@ -83,13 +83,12 @@ DevicePolicyCrosBrowserTest::~DevicePolicyCrosBrowserTest() {
 }
 
 void DevicePolicyCrosBrowserTest::SetUpInProcessBrowserTestFixture() {
-  chromeos::DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager_);
+  chromeos::DBusThreadManager::SetInstanceForTesting(fake_dbus_thread_manager_);
   InProcessBrowserTest::SetUpInProcessBrowserTestFixture();
 }
 
 void DevicePolicyCrosBrowserTest::TearDownInProcessBrowserTestFixture() {
   InProcessBrowserTest::TearDownInProcessBrowserTestFixture();
-  chromeos::DBusThreadManager::Shutdown();
 }
 
 void DevicePolicyCrosBrowserTest::MarkAsEnterpriseOwned() {
diff --git a/chrome/browser/chromeos/power/peripheral_battery_observer_browsertest.cc b/chrome/browser/chromeos/power/peripheral_battery_observer_browsertest.cc
index c14d41d..1e6e8e9 100644
--- a/chrome/browser/chromeos/power/peripheral_battery_observer_browsertest.cc
+++ b/chrome/browser/chromeos/power/peripheral_battery_observer_browsertest.cc
@@ -40,7 +40,7 @@ class PeripheralBatteryObserverTest : public InProcessBrowserTest {
     FakeDBusThreadManager* fake_dbus_thread_manager =
         new FakeDBusThreadManager;
     fake_dbus_thread_manager->SetFakeClients();
-    DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager);
+    DBusThreadManager::SetInstanceForTesting(fake_dbus_thread_manager);
     InProcessBrowserTest::SetUpInProcessBrowserTestFixture();
   }
 
@@ -54,7 +54,6 @@ class PeripheralBatteryObserverTest : public InProcessBrowserTest {
 
   virtual void TearDownInProcessBrowserTestFixture() OVERRIDE {
     InProcessBrowserTest::TearDownInProcessBrowserTestFixture();
-    DBusThreadManager::Shutdown();
   }
 
  protected:
diff --git a/chrome/browser/extensions/api/system_private/system_private_apitest.cc b/chrome/browser/extensions/api/system_private/system_private_apitest.cc
index b49b396..f242095 100644
--- a/chrome/browser/extensions/api/system_private/system_private_apitest.cc
+++ b/chrome/browser/extensions/api/system_private/system_private_apitest.cc
@@ -37,11 +37,11 @@ class GetUpdateStatusApiTest : public ExtensionApiTest {
     fake_update_engine_client_ = new chromeos::FakeUpdateEngineClient;
     fake_dbus_thread_manager->SetUpdateEngineClient(
         scoped_ptr<UpdateEngineClient>(fake_update_engine_client_));
-    chromeos::DBusThreadManager::InitializeForTesting(fake_dbus_thread_manager);
+    chromeos::DBusThreadManager::SetInstanceForTesting(
+        fake_dbus_thread_manager);
   }
 
   virtual void TearDownInProcessBrowserTestFixture() OVERRIDE {
-    chromeos::DBusThreadManager::Shutdown();
     ExtensionApiTest::TearDownInProcessBrowserTestFixture();
   }
 
diff --git a/chromeos/dbus/dbus_thread_manager.cc b/chromeos/dbus/dbus_thread_manager.cc
index 7a8a417..ab02152 100644
--- a/chromeos/dbus/dbus_thread_manager.cc
+++ b/chromeos/dbus/dbus_thread_manager.cc
@@ -51,7 +51,7 @@
 namespace chromeos {
 
 static DBusThreadManager* g_dbus_thread_manager = NULL;
-static bool g_dbus_thread_manager_set_for_testing = false;
+static DBusThreadManager* g_dbus_thread_manager_for_testing = NULL;
 
 // The DBusThreadManager implementation used in production.
 class DBusThreadManagerImpl : public DBusThreadManager {
@@ -319,13 +319,16 @@ class DBusThreadManagerImpl : public DBusThreadManager {
 
 // static
 void DBusThreadManager::Initialize() {
-  // Ignore Initialize() if we set a test DBusThreadManager.
-  if (g_dbus_thread_manager_set_for_testing)
-    return;
   // If we initialize DBusThreadManager twice we may also be shutting it down
   // early; do not allow that.
   CHECK(g_dbus_thread_manager == NULL);
 
+  if (g_dbus_thread_manager_for_testing) {
+    g_dbus_thread_manager = g_dbus_thread_manager_for_testing;
+    InitializeClients();
+    VLOG(1) << "DBusThreadManager initialized with test implementation";
+    return;
+  }
   // Determine whether we use stub or real client implementations.
   if (base::SysInfo::IsRunningOnChromeOS()) {
     g_dbus_thread_manager = new DBusThreadManagerImpl;
@@ -333,21 +336,22 @@ void DBusThreadManager::Initialize() {
     VLOG(1) << "DBusThreadManager initialized for ChromeOS";
   } else {
     InitializeWithStub();
-    return;
   }
 }
 
 // static
+void DBusThreadManager::SetInstanceForTesting(
+    DBusThreadManager* dbus_thread_manager) {
+  CHECK(!g_dbus_thread_manager);
+  CHECK(!g_dbus_thread_manager_for_testing);
+  g_dbus_thread_manager_for_testing = dbus_thread_manager;
+}
+
+// static
 void DBusThreadManager::InitializeForTesting(
     DBusThreadManager* dbus_thread_manager) {
-  // If we initialize DBusThreadManager twice we may also be shutting it down
-  // early; do not allow that.
-  CHECK(g_dbus_thread_manager == NULL);
-  CHECK(dbus_thread_manager);
-  g_dbus_thread_manager = dbus_thread_manager;
-  g_dbus_thread_manager_set_for_testing = true;
-  InitializeClients();
-  VLOG(1) << "DBusThreadManager initialized with test implementation";
+  SetInstanceForTesting(dbus_thread_manager);
+  Initialize();
 }
 
 // static
@@ -372,9 +376,10 @@ bool DBusThreadManager::IsInitialized() {
 void DBusThreadManager::Shutdown() {
   // If we called InitializeForTesting, this may get called more than once.
   // Ensure that we only shutdown DBusThreadManager once.
-  CHECK(g_dbus_thread_manager || g_dbus_thread_manager_set_for_testing);
+  CHECK(g_dbus_thread_manager || g_dbus_thread_manager_for_testing);
   DBusThreadManager* dbus_thread_manager = g_dbus_thread_manager;
   g_dbus_thread_manager = NULL;
+  g_dbus_thread_manager_for_testing = NULL;
   delete dbus_thread_manager;
   VLOG(1) << "DBusThreadManager Shutdown completed";
 }
@@ -389,9 +394,9 @@ DBusThreadManager::~DBusThreadManager() {
     return;  // Called form Shutdown() or local test instance.
   // There should never be both a global instance and a local instance.
   CHECK(this == g_dbus_thread_manager);
-  if (g_dbus_thread_manager_set_for_testing) {
+  if (g_dbus_thread_manager_for_testing) {
     g_dbus_thread_manager = NULL;
-    g_dbus_thread_manager_set_for_testing = false;
+    g_dbus_thread_manager_for_testing = NULL;
     VLOG(1) << "DBusThreadManager destroyed";
   } else {
     LOG(FATAL) << "~DBusThreadManager() called outside of Shutdown()";
diff --git a/chromeos/dbus/dbus_thread_manager.h b/chromeos/dbus/dbus_thread_manager.h
index c980b27..c36ddc3 100644
--- a/chromeos/dbus/dbus_thread_manager.h
+++ b/chromeos/dbus/dbus_thread_manager.h
@@ -83,10 +83,18 @@ class CHROMEOS_EXPORT DBusThreadManager {
   // making it a Singleton, to ensure clean startup and shutdown.
   static void Initialize();
 
-  // Similar to Initialize(), but can inject an alternative
-  // DBusThreadManager such as MockDBusThreadManager for testing.
-  // The injected object will be owned by the internal pointer and deleted
-  // by Shutdown().
+  // Sets an alternative DBusThreadManager such as MockDBusThreadManager
+  // to be used in |Initialize()| for testing. Tests that call
+  // DBusThreadManager::Initialize() (such as browser_tests and
+  // interactive_ui_tests) should use this instead of calling
+  // |InitiailzeForTesting|.  The injected object will be owned by the
+  // internal pointer and deleted by Shutdown().
+  static void SetInstanceForTesting(DBusThreadManager* dbus_thread_manager);
+
+  // Similar to Initialize(), but injects an alternative
+  // DBusThreadManager using SetInstanceForTest first.  The injected
+  // object will be owned by the internal pointer and deleted by
+  // Shutdown().
   static void InitializeForTesting(DBusThreadManager* dbus_thread_manager);
 
   // Initialize with stub implementations for tests based on stubs.
diff --git a/content/browser/renderer_host/render_sandbox_host_linux.cc b/content/browser/renderer_host/render_sandbox_host_linux.cc
index a018043..d17b1ca 100644
--- a/content/browser/renderer_host/render_sandbox_host_linux.cc
+++ b/content/browser/renderer_host/render_sandbox_host_linux.cc
@@ -709,10 +709,9 @@ void RenderSandboxHostLinux::Init(const std::string& sandbox_path) {
   childs_lifeline_fd_ = pipefds[1];
 
   // We need to be monothreaded before we fork().
-#if !defined(TOOLKIT_GTK) && !defined(OS_CHROMEOS)
+#if !defined(TOOLKIT_GTK)
   // Exclude gtk port as TestSuite in base/tests/test_suite.cc is calling
   // gtk_init.
-  // Exclude ChromeOS because KioskTest spawns EmbeddedTestServer.
   // TODO(oshima): Remove ifdef when above issues are resolved.
   DCHECK_EQ(1, base::GetNumberOfThreads(base::GetCurrentProcessHandle()));
 #endif
diff --git a/content/public/test/browser_test_base.cc b/content/public/test/browser_test_base.cc
index 871c271..5587180 100644
--- a/content/public/test/browser_test_base.cc
+++ b/content/public/test/browser_test_base.cc
@@ -216,9 +216,7 @@ void BrowserTestBase::SetUp() {
   rule_based_resolver_->AddSimulatedFailure("wpad");
   net::ScopedDefaultHostResolverProc scoped_local_host_resolver_proc(
       rule_based_resolver_.get());
-
   SetUpInProcessBrowserTestFixture();
-
   MainFunctionParams params(*command_line);
   params.ui_task =
       new base::Closure(
diff --git a/net/test/embedded_test_server/embedded_test_server.cc b/net/test/embedded_test_server/embedded_test_server.cc
index 3d246d1..aacecd2 100644
--- a/net/test/embedded_test_server/embedded_test_server.cc
+++ b/net/test/embedded_test_server/embedded_test_server.cc
@@ -99,6 +99,10 @@ HttpListenSocket::~HttpListenSocket() {
   DCHECK(thread_checker_.CalledOnValidThread());
 }
 
+void HttpListenSocket::DetachFromThread() {
+  thread_checker_.DetachFromThread();
+}
+
 EmbeddedTestServer::EmbeddedTestServer()
     : port_(-1),
       weak_factory_(this) {
@@ -114,21 +118,28 @@ EmbeddedTestServer::~EmbeddedTestServer() {
 }
 
 bool EmbeddedTestServer::InitializeAndWaitUntilReady() {
-  base::Thread::Options thread_options;
-  thread_options.message_loop_type = base::MessageLoop::TYPE_IO;
-  io_thread_.reset(new base::Thread("EmbeddedTestServer io thread"));
-  CHECK(io_thread_->StartWithOptions(thread_options));
-
+  StartThread();
   DCHECK(thread_checker_.CalledOnValidThread());
-
   if (!PostTaskToIOThreadAndWait(base::Bind(
           &EmbeddedTestServer::InitializeOnIOThread, base::Unretained(this)))) {
     return false;
   }
-
   return Started() && base_url_.is_valid();
 }
 
+void EmbeddedTestServer::StopThread() {
+  io_thread_->Stop();
+  io_thread_.reset();
+  thread_checker_.DetachFromThread();
+  listen_socket_->DetachFromThread();
+}
+
+void EmbeddedTestServer::RestartThreadAndListen() {
+  StartThread();
+  CHECK(PostTaskToIOThreadAndWait(base::Bind(
+      &EmbeddedTestServer::ListenOnIOThread, base::Unretained(this))));
+}
+
 bool EmbeddedTestServer::ShutdownAndWaitUntilComplete() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
@@ -136,6 +147,14 @@ bool EmbeddedTestServer::ShutdownAndWaitUntilComplete() {
       &EmbeddedTestServer::ShutdownOnIOThread, base::Unretained(this)));
 }
 
+void EmbeddedTestServer::StartThread() {
+  DCHECK(!io_thread_.get());
+  base::Thread::Options thread_options;
+  thread_options.message_loop_type = base::MessageLoop::TYPE_IO;
+  io_thread_.reset(new base::Thread("EmbeddedTestServer io thread"));
+  CHECK(io_thread_->StartWithOptions(thread_options));
+}
+
 void EmbeddedTestServer::InitializeOnIOThread() {
   DCHECK(io_thread_->message_loop_proxy()->BelongsToCurrentThread());
   DCHECK(!Started());
@@ -157,6 +176,12 @@ void EmbeddedTestServer::InitializeOnIOThread() {
   }
 }
 
+void EmbeddedTestServer::ListenOnIOThread() {
+  DCHECK(io_thread_->message_loop_proxy()->BelongsToCurrentThread());
+  DCHECK(Started());
+  listen_socket_->Listen();
+}
+
 void EmbeddedTestServer::ShutdownOnIOThread() {
   DCHECK(io_thread_->message_loop_proxy()->BelongsToCurrentThread());
 
diff --git a/net/test/embedded_test_server/embedded_test_server.h b/net/test/embedded_test_server/embedded_test_server.h
index d5300b4..5600e0f 100644
--- a/net/test/embedded_test_server/embedded_test_server.h
+++ b/net/test/embedded_test_server/embedded_test_server.h
@@ -39,6 +39,10 @@ class HttpListenSocket : public TCPListenSocket {
   virtual void Listen();
 
  private:
+  friend class EmbeddedTestServer;
+
+  // Detaches the current from |thread_checker_|.
+  void DetachFromThread();
 
   base::ThreadChecker thread_checker_;
 };
@@ -48,18 +52,10 @@ class HttpListenSocket : public TCPListenSocket {
 // it assumes that the request syntax is correct. It *does not* support
 // a Chunked Transfer Encoding.
 //
-// The common use case is below:
-//
-// base::Thread io_thread_;
-// scoped_ptr<EmbeddedTestServer> test_server_;
+// The common use case for unit tests is below:
 //
 // void SetUp() {
-//   base::Thread::Options thread_options;
-//   thread_options.message_loop_type = base::MessageLoop::TYPE_IO;
-//   ASSERT_TRUE(io_thread_.StartWithOptions(thread_options));
-//
-//   test_server_.reset(
-//       new EmbeddedTestServer(io_thread_.message_loop_proxy()));
+//   test_server_.reset(new EmbeddedTestServer());
 //   ASSERT_TRUE(test_server_.InitializeAndWaitUntilReady());
 //   test_server_->RegisterRequestHandler(
 //       base::Bind(&FooTest::HandleRequest, base::Unretained(this)));
@@ -77,6 +73,24 @@ class HttpListenSocket : public TCPListenSocket {
 //   return http_response.Pass();
 // }
 //
+// For a test that spawns another process such as browser_tests, you
+// need to stop the server's thread so that there is no no other
+// threads running while spawning the process. To do so, please follow
+// the following example:
+//
+// void SetUp() {
+//   test_server_.reset(new EmbeddedTestServer());
+//   // EmbeddedTestServer spawns a thread to initialize socket.
+//   // Stop the thread in preparation for fork and exec.
+//   test_server_->StopThread();
+//   ...
+//   InProcessBrowserTest::SetUp();
+// }
+//
+// void SetUpOnMainThread() {
+//   test_server_->RestartThreadAndListen();
+// }
+//
 class EmbeddedTestServer : public StreamListenSocket::Delegate {
  public:
   typedef base::Callback<scoped_ptr<HttpResponse>(
@@ -122,10 +136,19 @@ class EmbeddedTestServer : public StreamListenSocket::Delegate {
   // on UI thread.
   void RegisterRequestHandler(const HandleRequestCallback& callback);
 
+  // Stops IO thread that handles http requests.
+  void StopThread();
+
+  // Restarts IO thread and listen on the socket.
+  void RestartThreadAndListen();
+
  private:
+  void StartThread();
+
   // Initializes and starts the server. If initialization succeeds, Starts()
   // will return true.
   void InitializeOnIOThread();
+  void ListenOnIOThread();
 
   // Shuts down the server.
   void ShutdownOnIOThread();