Use multi-profile mount point by default after browser crash and in Guest session.

chrome/browser/chromeos/profiles/profile_helper.h

Index: chrome/browser/chromeos/profiles/profile_helper.h
diff --git a/chrome/browser/chromeos/profiles/profile_helper.h b/chrome/browser/chromeos/profiles/profile_helper.h
index 611690ff90f4d32da3f419b78ee902b7116f35e5..2d11609a53a232ad80921203bd728849810f3433 100644
--- a/chrome/browser/chromeos/profiles/profile_helper.h
+++ b/chrome/browser/chromeos/profiles/profile_helper.h
@@ -63,6 +63,9 @@ class ProfileHelper : public BrowsingDataRemover::Observer,
   // Returns active user profile dir in a format [u-$hash].
   base::FilePath GetActiveUserProfileDir();
 
+  // Returns user profile dir in a format [u-user_id_hash].
+  base::FilePath GetUserProfileDir(const std::string& user_id_hash);
+
   // Should called once after UserManager instance has been created.
   void Initialize();