If possible, use the PathService instead of the --user-data-dir flag directly

chrome/service/cloud_print/cloud_print_proxy.cc

 // Copyright (c) 2012 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/service/cloud_print/cloud_print_proxy.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
@@ skipping 16 matching lines @@
 void LaunchBrowserProcessWithSwitch(const std::string& switch_string) {
   DCHECK(g_service_process->io_thread()->message_loop_proxy()->
       BelongsToCurrentThread());
   base::FilePath exe_path;
   PathService::Get(base::FILE_EXE, &exe_path);
   if (exe_path.empty()) {
     NOTREACHED() << "Unable to get browser process binary name.";
   }
   base::CommandLine cmd_line(exe_path);
 
+  // Propagate an explicit --user-data-dir value if one was given. The new
+  // browser process will pick up a policy override during initialization.
   const base::CommandLine& process_command_line =
       *base::CommandLine::ForCurrentProcess();
   base::FilePath user_data_dir =
       process_command_line.GetSwitchValuePath(switches::kUserDataDir);
   if (!user_data_dir.empty())
     cmd_line.AppendSwitchPath(switches::kUserDataDir, user_data_dir);
   cmd_line.AppendSwitch(switch_string);
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
   base::Process process = base::LaunchProcess(cmd_line, base::LaunchOptions());
@@ skipping 240 matching lines @@
 }
 
 void CloudPrintProxy::ShutdownBackend() {
   DCHECK(CalledOnValidThread());
   if (backend_.get())
     backend_->Shutdown();
   backend_.reset();
 }
 
 }  // namespace cloud_print