CommandLine: add a CopySwitchesFrom() for copying from another CommandLine

chrome/browser/process_singleton_uitest.cc

 // Copyright (c) 2010 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.
 
 // This test validates that the ProcessSingleton class properly makes sure
 // that there is only one main browser process.
 //
 // It is currently compiled and run on Windows and Posix(non-Mac) platforms.
 // Mac uses system services and ProcessSingletonMac is a noop.  (Maybe it still
 // makes sense to test that the system services are giving the behavior we
@@ skipping 44 matching lines @@
   void StartChrome(base::WaitableEvent* start_event, bool first_run) {
     // TODO(mattm): maybe stuff should be refactored to use
     // UITest::LaunchBrowserHelper somehow?
     FilePath browser_directory;
     PathService::Get(chrome::DIR_APP, &browser_directory);
     CommandLine command_line(browser_directory.Append(
         FilePath::FromWStringHack(chrome::kBrowserProcessExecutablePath)));
 
     FilePath user_data_directory;
     PathService::Get(chrome::DIR_USER_DATA, &user_data_directory);
-    command_line.AppendSwitchWithValue(switches::kUserDataDir,
-                                       user_data_directory.ToWStringHack());
+    command_line.AppendSwitchPath(switches::kUserDataDir, user_data_directory);
 
     if (first_run)
       command_line.AppendSwitch(switches::kFirstRun);
     else
       command_line.AppendSwitch(switches::kNoFirstRun);
 
     // Try to get all threads to launch the app at the same time.
     // So let the test know we are ready.
     ready_event_.Signal();
     // And then wait for the test to tell us to GO!
@@ skipping 217 matching lines @@
     pending_starters.empty();
     if (chrome_starters_[last_index]->process_handle_ !=
         base::kNullProcessHandle) {
       KillProcessTree(chrome_starters_[last_index]->process_handle_);
       chrome_starters_[last_index]->done_event_.Wait();
     }
   }
 }
 
 }  // namespace