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

components/browser_watcher/exit_code_watcher_win_unittest.cc

 // Copyright (c) 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 "components/browser_watcher/exit_code_watcher_win.h"
 
 #include "base/command_line.h"
 #include "base/process/process.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
@@ skipping 21 matching lines @@
 }
 
 class ScopedSleeperProcess {
  public:
    ScopedSleeperProcess() : is_killed_(false) {
   }
 
   ~ScopedSleeperProcess() {
     if (process_.IsValid()) {
       process_.Terminate(-1, false);
-      int exit_code = 0;
-      EXPECT_TRUE(process_.WaitForExit(&exit_code));
+      EXPECT_TRUE(process_.WaitForExit(nullptr));
     }
   }
 
   void Launch() {
     ASSERT_FALSE(process_.IsValid());
 
     base::CommandLine cmd_line(base::GetMultiProcessTestChildBaseCommandLine());
     base::LaunchOptions options;
     options.start_hidden = true;
     process_ = base::SpawnMultiProcessTestChild("Sleeper", cmd_line, options);
@@ skipping 107 matching lines @@
   // Kill the sleeper, and make sure it's exited before we continue.
   ASSERT_NO_FATAL_FAILURE(sleeper.Kill(kExitCode, true));
 
   watcher.WaitForExit();
   EXPECT_EQ(kExitCode, watcher.exit_code());
 
   VerifyWroteExitCode(sleeper.process().Pid(), kExitCode);
 }
 
 }  // namespace browser_watcher