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

chrome/browser/ui/views/profiles/user_manager_view.h

 // Copyright 2014 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_BROWSER_UI_VIEWS_PROFILES_USER_MANAGER_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_PROFILES_USER_MANAGER_VIEW_H_
 
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_window.h"
 #include "ui/views/window/dialog_delegate.h"
@@ skipping 17 matching lines @@
   // Hide the User Manager.
   static void Hide();
 
   // Returns whether or not the User Manager is showing.
   static bool IsShowing();
 
  private:
   explicit UserManagerView(Profile* profile);
   virtual ~UserManagerView();
 
-  // Creates a new UserManagerView instance for the |guest_profile| and
-  // shows the |url|.
-  static void OnGuestProfileCreated(Profile* guest_profile,
-                                    const std::string& url);
+  // Creates a new UserManagerView instance for |profile| and shows the |url|.
+  static void OnUserManagerProfileCreated(Profile* profile,
+                                          const std::string& url);
 
   // views::View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
 
   // views::DialogDelegateView:
   virtual bool CanResize() const OVERRIDE;
   virtual bool CanMaximize() const OVERRIDE;
   virtual base::string16 GetWindowTitle() const OVERRIDE;
   virtual int GetDialogButtons() const OVERRIDE;
   virtual void WindowClosing() OVERRIDE;
   virtual bool UseNewStyleForThisDialog() const OVERRIDE;
 
   views::WebView* web_view_;
 
   scoped_ptr<AutoKeepAlive> keep_alive_;
   // An open User Manager window. There can only be one open at a time. This
   // is reset to NULL when the window is closed.
   static UserManagerView* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(UserManagerView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PROFILES_USER_MANAGER_VIEW_H_