ChromeOS cryptohome should be able to use gaia id as user identifier.

chrome/test/base/testing_profile_manager.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 "chrome/test/base/testing_profile_manager.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/memory/ref_counted.h"
@@ skipping 69 matching lines @@
   }
 #else
   profile_path = profile_path.AppendASCII(profile_name);
 #endif
 
   // Create the profile and register it.
   TestingProfile::Builder builder;
   builder.SetPath(profile_path);
   builder.SetPrefService(std::move(prefs));
   builder.SetSupervisedUserId(supervised_user_id);
+  builder.SetProfileName(profile_name);
 
   for (TestingProfile::TestingFactories::const_iterator it = factories.begin();
        it != factories.end(); ++it) {
     builder.AddTestingFactory(it->first, it->second);
   }
 
   TestingProfile* profile = builder.Build().release();
-  profile->set_profile_name(profile_name);
   profile_manager_->AddProfile(profile);  // Takes ownership.
 
   // Update the user metadata.
   ProfileInfoCache& cache = profile_manager_->GetProfileInfoCache();
   size_t index = cache.GetIndexOfProfileWithPath(profile_path);
   cache.SetAvatarIconOfProfileAtIndex(index, avatar_id);
   cache.SetSupervisedUserIdOfProfileAtIndex(index, supervised_user_id);
   // SetNameOfProfileAtIndex may reshuffle the list of profiles, so we do it
   // last.
   cache.SetNameOfProfileAtIndex(index, user_name);
@@ skipping 139 matching lines @@
   // Set up the directory for profiles.
   ASSERT_TRUE(profiles_dir_.CreateUniqueTempDir());
 
   profile_manager_ = new testing::ProfileManager(profiles_dir_.path());
   browser_process_->SetProfileManager(profile_manager_);  // Takes ownership.
 
   profile_manager_->GetProfileInfoCache().
       set_disable_avatar_download_for_testing(true);
   called_set_up_ = true;
 }