Enable profile switching for standalone App Launcher via the Settings App.

chrome/browser/profiles/profile_manager.h

Index: chrome/browser/profiles/profile_manager.h
diff --git a/chrome/browser/profiles/profile_manager.h b/chrome/browser/profiles/profile_manager.h
index 9d1e03f7be98e6f2588722ed9ca352026de91515..8c884dd4266ce3388efa3b29f283b83fe94f3fcf 100644
--- a/chrome/browser/profiles/profile_manager.h
+++ b/chrome/browser/profiles/profile_manager.h
@@ -101,6 +101,10 @@ class ProfileManager : public base::NonThreadSafe,
   // Same as instance method but provides the default user_data_dir as well.
   static Profile* GetLastUsedProfile();
 
+  // Get the path of the last used profile, or if that's undefined, the default
+  // profile.
+  FilePath GetLastUsedProfilePath(const FilePath& user_data_dir);

[sail, 2013/01/23 16:55:24]

The profile manager class is way to big right now. One problem is that it has
multiple ways to do the same thing. This makes it hard to maintain and hard to
understand.

Is there anyway we can avoid adding yet another way to get the last used
profile? If not can you remove GetLastUsedProfile and convert everyone to use
your new function?

[koz (OOO until 15th September), 2013/01/25 00:32:46]

I think the existence of these related functions is a result of the fact that
ProfileManager is responsible for loading profiles as well as managing these
preferences; there's already analogous methods GetDefaultProfile() and
GetDefaultProfileDir().

[sail, 2013/01/25 18:22:34]

Argh. I'd like to avoid this. If you can't figure out a better solution then
lets at least match the naming convention in GetDefaultProfile*().

[koz (OOO until 15th September), 2013/01/29 00:34:11]

Unfortunately a better way doesn't jump out at me, so I've done the rename :-(

+
   // Get the Profiles which are currently open, i.e., have open browsers, or
   // were open the last time Chrome was running. The Profiles appear in the
   // order they were opened. The last used profile will be on the list, but its