Introduce the ability to wait for the watcher process to initialize.

chrome/app/chrome_watcher_command_line_unittest_win.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 "chrome/app/chrome_watcher_command_line_win.h"
 
+#include <windows.h>
+
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/process/process_handle.h"
 #include "base/win/scoped_handle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 TEST(ChromeWatcherCommandLineTest, BasicTest) {
   base::ProcessHandle current = nullptr;
   ASSERT_TRUE(base::OpenProcessHandle(base::GetCurrentProcId(), &current));
-  base::CommandLine cmd_line =
-      GenerateChromeWatcherCommandLine(base::FilePath(L"example.exe"), current);
-  base::win::ScopedHandle result = InterpretChromeWatcherCommandLine(cmd_line);
-  ASSERT_EQ(current, result.Get());
+  HANDLE event = ::CreateEvent(nullptr, FALSE, FALSE, nullptr);
+
+  base::CommandLine cmd_line = GenerateChromeWatcherCommandLine(
+      base::FilePath(L"example.exe"), event, current);
+
+  base::win::ScopedHandle current_result;
+  base::win::ScopedHandle event_result;
+  ASSERT_TRUE(InterpretChromeWatcherCommandLine(cmd_line, &event_result,
+                                                &current_result));
+  ASSERT_EQ(current, current_result.Get());
+  ASSERT_EQ(event, event_result.Get());
 }