Handled nullptr argument in WaitForExit() and WaitForExitWithTimeout() methods.

chrome/browser/process_singleton_win_unittest.cc

 // Copyright 2015 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 "chrome/browser/process_singleton.h"
 
 #include <windows.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 143 matching lines @@
     // Drop the process finder notification timeout to one second for testing.
     old_notification_timeout_ = chrome::SetNotificationTimeoutForTesting(
         base::TimeDelta::FromSeconds(1));
   }
 
   void TearDown() override {
     chrome::SetNotificationTimeoutForTesting(old_notification_timeout_);
 
     if (browser_victim_.IsValid()) {
       EXPECT_TRUE(::SetEvent(continue_event_.Get()));
-      int exit_code = 0;
-      EXPECT_TRUE(browser_victim_.WaitForExit(&exit_code));
+      EXPECT_TRUE(browser_victim_.WaitForExit(nullptr));
     }
 
     base::MultiProcessTest::TearDown();
   }
 
   void LaunchHungBrowserProcess(WindowOption window_option) {
     // Create a unique user data dir to rendezvous on.
     ASSERT_TRUE(user_data_dir_.CreateUniqueTempDir());
 
     // Create the named "ready" event, this is unique to our process.
@@ skipping 133 matching lines @@
   // visible window.
   EXPECT_TRUE(should_kill_called());
 
   // Verify that the hung browser has beem terminated with the
   // RESULT_CODE_HUNG exit code.
   int exit_code = 0;
   EXPECT_TRUE(
       browser_victim()->WaitForExitWithTimeout(base::TimeDelta(), &exit_code));
   EXPECT_EQ(content::RESULT_CODE_HUNG, exit_code);
 }