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

chrome/browser/shell_integration.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/browser/shell_integration.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_util.h"
+#include "base/path_service.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "chrome/browser/policy/policy_path_parser.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "content/public/browser/browser_thread.h"
 
 #if defined(OS_CHROMEOS)
@@ skipping 55 matching lines @@
     // Note: Do not change this flag!  Old Gears shortcuts will break if you do!
     new_cmd_line.AppendSwitchASCII(switches::kApp, url.spec());
   }
   return new_cmd_line;
 }
 
 // static
 void ShellIntegration::AppendProfileArgs(const base::FilePath& profile_path,
                                          base::CommandLine* command_line) {
   DCHECK(command_line);
-  const base::CommandLine& cmd_line = *base::CommandLine::ForCurrentProcess();
 
   // Use the same UserDataDir for new launches that we currently have set.
-  base::FilePath user_data_dir =
-      cmd_line.GetSwitchValuePath(switches::kUserDataDir);
+  base::FilePath user_data_dir;
+  PathService::Get(chrome::DIR_USER_DATA, &user_data_dir);
 #if defined(OS_MACOSX) || defined(OS_WIN)
   policy::path_parser::CheckUserDataDirPolicy(&user_data_dir);

[grt (UTC plus 2), 2015/03/26 18:36:22]

this isn't needed now, is it?

[noms (inactive), 2015/03/30 14:06:32]

Done.

 #endif
   if (!user_data_dir.empty()) {
     // Make sure user_data_dir is an absolute path.
     user_data_dir = base::MakeAbsoluteFilePath(user_data_dir);
     if (!user_data_dir.empty() && base::PathExists(user_data_dir))
       command_line->AppendSwitchPath(switches::kUserDataDir, user_data_dir);
   }
 
 #if defined(OS_CHROMEOS)
+  const base::CommandLine& cmd_line = *base::CommandLine::ForCurrentProcess();
   base::FilePath profile = cmd_line.GetSwitchValuePath(
       chromeos::switches::kLoginProfile);
   if (!profile.empty())
     command_line->AppendSwitchPath(chromeos::switches::kLoginProfile, profile);
 #else
   if (!profile_path.empty())
     command_line->AppendSwitchPath(switches::kProfileDirectory,
                                    profile_path.BaseName());
 #endif
 }
@@ skipping 194 matching lines @@
     case ShellIntegration::SET_DEFAULT_INTERACTIVE:
       if (interactive_permitted) {
         result = ShellIntegration::SetAsDefaultProtocolClientInteractive(
             protocol_);
       }
       break;
   }
 
   return result;
 }