The User Manager should be backed by a special profile, not the guest one.

chrome/test/base/testing_profile_manager.h

 // 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.
 
 #ifndef CHROME_TEST_BASE_TESTING_PROFILE_MANAGER_H_
 #define CHROME_TEST_BASE_TESTING_PROFILE_MANAGER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 49 matching lines @@
   // Small helper for creating testing profiles. Just forwards to above.
   TestingProfile* CreateTestingProfile(const std::string& name);
 
   // Creates a new guest TestingProfile whose data lives in the guest profile
   // test environment directory, as specified by the profile manager.
   // This profile will not be added to the ProfileInfoCache. This will
   // register the TestingProfile with the profile subsystem as well.
   // The subsystem owns the Profile and returns a weak pointer.
   TestingProfile* CreateGuestProfile();
 
+  // Creates a TestingProfile whose data lives in the User Manager profile
+  // test environment directory, as specified by the profile manager.
+  // This profile will not be added to the ProfileInfoCache. This will
+  // register the TestingProfile with the profile subsystem as well.
+  // The subsystem owns the Profile and returns a weak pointer.
+  TestingProfile* CreateUserManagerProfile();
+
   // Deletes a TestingProfile from the profile subsystem.
   void DeleteTestingProfile(const std::string& profile_name);
 
-  // Deletes a guest TestingProfile from the profile manager.
-  void DeleteGuestProfile();
+  // Deletes a TestingProfile with |path| from the profile subsystem.
+  void DeleteProfileWithPath(const base::FilePath& path);
 
   // Deletes the cache instance. This is useful for testing that the cache is
   // properly persisting data.
   void DeleteProfileInfoCache();
 
   // Sets ProfileManager's logged_in state. This is only useful on ChromeOS.
   void SetLoggedIn(bool logged_in);
 
   // Helper accessors.
   const base::FilePath& profiles_dir();
@@ skipping 23 matching lines @@
   // Weak reference to the profile manager.
   ProfileManager* profile_manager_;
 
   // Map of profile_name to TestingProfile* from CreateTestingProfile().
   TestingProfilesMap testing_profiles_;
 
   DISALLOW_COPY_AND_ASSIGN(TestingProfileManager);
 };
 
 #endif  // CHROME_TEST_BASE_TESTING_PROFILE_MANAGER_H_