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

chrome/browser/profiles/profile_manager_unittest.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 <string>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/path_service.h"
@@ skipping 339 matching lines @@
   EXPECT_EQ(2u, cache.GetNumberOfProfiles());
   size_t managed_index = cache.GetIndexOfProfileWithPath(managed_path);
   EXPECT_TRUE(cache.IsOmittedProfileAtIndex(managed_index));
   size_t nonmanaged_index = cache.GetIndexOfProfileWithPath(nonmanaged_path);
   EXPECT_FALSE(cache.IsOmittedProfileAtIndex(nonmanaged_index));
 }
 
 TEST_F(ProfileManagerTest, GetGuestProfilePath) {
   base::FilePath guest_path = ProfileManager::GetGuestProfilePath();
   base::FilePath expected_path = temp_dir_.path();
-  expected_path = expected_path.Append(chrome::kGuestProfileDir);
+  expected_path = expected_path.AppendASCII(chrome::kGuestProfileDir);
   EXPECT_EQ(expected_path, guest_path);
 }
 
+TEST_F(ProfileManagerTest, GetUserManagerProfilePath) {
+  base::FilePath path = ProfileManager::GetUserManagerProfilePath();
+  base::FilePath expected_path = temp_dir_.path();
+  expected_path = expected_path.AppendASCII(chrome::kUserManagerProfileDir);
+  EXPECT_EQ(expected_path, path);
+}
+
 class UnittestGuestProfileManager : public UnittestProfileManager {
  public:
   explicit UnittestGuestProfileManager(const base::FilePath& user_data_dir)
       : UnittestProfileManager(user_data_dir) {}
 
  protected:
   virtual Profile* CreateProfileHelper(
       const base::FilePath& file_path) OVERRIDE {
     TestingProfile::Builder builder;
     builder.SetGuestSession();
@@ skipping 732 matching lines @@
                          dest_path2.BaseName().MaybeAsASCII());
   profile_manager->ScheduleProfileForDeletion(dest_path2,
                                               ProfileManager::CreateCallback());
   // Spin the message loop so that all the callbacks can finish running.
   base::RunLoop().RunUntilIdle();
 
   EXPECT_EQ(dest_path3, profile_manager->GetLastUsedProfile()->GetPath());
   EXPECT_EQ(profile_name3, local_state->GetString(prefs::kProfileLastUsed));
 }
 #endif  // !defined(OS_MACOSX)