When enabling new profile management programmatically, make sure to set the

chrome/browser/profiles/profile_window.cc

 // Copyright 2013 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/browser/profiles/profile_window.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 303 matching lines @@
   } else {
     chrome::ShowUserManagerWithTutorial(
         profiles::USER_MANAGER_TUTORIAL_OVERVIEW);
   }
 }
 
 void EnableNewProfileManagementPreview(Profile* profile) {
 #if defined(OS_ANDROID)
   NOTREACHED();
 #else
+  // TODO(rogerta): instead of setting experiment flags and command line
+  // args, we should set a profile preference.
+  const about_flags::Experiment experiment = {
+      kNewProfileManagementExperimentInternalName,
+      0,  // string id for title of experiment
+      0,  // string id for description of experiment

[noms (inactive), 2014/06/20 14:44:19]

optional nit: Do these have to be capitalized and end in a period? (I don't
know)

+      0,  // supported platforms
+      about_flags::Experiment::ENABLE_DISABLE_VALUE,
+      switches::kEnableNewProfileManagement,
+      "",  // not used with ENABLE_DISABLE_VALUE type
+      switches::kDisableNewProfileManagement,
+      "",  // not used with ENABLE_DISABLE_VALUE type
+      NULL,  // not used with ENABLE_DISABLE_VALUE type
+      3
+  };
   about_flags::PrefServiceFlagsStorage flags_storage(
       g_browser_process->local_state());
   about_flags::SetExperimentEnabled(
       &flags_storage,
-      kNewProfileManagementExperimentInternalName,
+      experiment.NameForChoice(1),
       true);
 
   switches::EnableNewProfileManagementForTesting(
       CommandLine::ForCurrentProcess());
   chrome::ShowUserManagerWithTutorial(profiles::USER_MANAGER_TUTORIAL_OVERVIEW);
   UpdateServicesWithNewProfileManagementFlag(profile, true);
 #endif
 }
 
 void DisableNewProfileManagementPreview(Profile* profile) {
   about_flags::PrefServiceFlagsStorage flags_storage(
       g_browser_process->local_state());
   about_flags::SetExperimentEnabled(
       &flags_storage,
       kNewProfileManagementExperimentInternalName,
       false);
   chrome::AttemptRestart();
   UpdateServicesWithNewProfileManagementFlag(profile, false);
 }
 
 }  // namespace profiles