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

chrome/browser/ui/views/app_list/win/app_list_service_win.cc

Index: chrome/browser/ui/views/app_list/win/app_list_service_win.cc
diff --git a/chrome/browser/ui/views/app_list/win/app_list_service_win.cc b/chrome/browser/ui/views/app_list/win/app_list_service_win.cc
index ba5d1550d9595158c82c75e19de7736c0cb0ac14..3bc1d095c0caead056ab84b8867445af07f3f3d0 100644
--- a/chrome/browser/ui/views/app_list/win/app_list_service_win.cc
+++ b/chrome/browser/ui/views/app_list/win/app_list_service_win.cc
@@ -32,6 +32,7 @@
 #include "chrome/browser/ui/views/app_list/win/app_list_win.h"
 #include "chrome/browser/web_applications/web_app.h"
 #include "chrome/common/chrome_constants.h"
+#include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
 #include "chrome/common/pref_names.h"
@@ -126,11 +127,9 @@ base::string16 GetAppModelId() {
   // but different for different user data directories, so base it on the
   // initial profile in the current user data directory.
   base::FilePath initial_profile_path;
-  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();

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

i hate to say it, but leave this one alone. it would be bad to change the app
model id in this case.

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

Done.

-  if (command_line->HasSwitch(switches::kUserDataDir)) {
-    initial_profile_path =
-        command_line->GetSwitchValuePath(switches::kUserDataDir).AppendASCII(
-            chrome::kInitialProfile);
+  if (PathService::Get(chrome::DIR_USER_DATA, &initial_profile_path)) {
+    initial_profile_path = initial_profile_path.AppendASCII(
+        chrome::kInitialProfile);
   }
   return ShellIntegration::GetAppListAppModelIdForProfile(initial_profile_path);
 }