Access to Chrome via the System Tray should go through the User Manager.

chrome/browser/ui/cocoa/profiles/user_manager_mac.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_COCOA_PROFILES_USER_MANAGER_MAC_H_
 #define CHROME_BROWSER_UI_COCOA_PROFILES_USER_MANAGER_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_window.h"
 
 @class UserManagerWindowController;
 
 namespace content {
 class NavigationController;
 class WebContents;
 }
 
 // Dialog widget that contains the Desktop User Manager webui.
 class UserManagerMac {
  public:
-  // Shows the User Manager or re-activates an existing one, focusing the
-  // profile given by |profile_path_to_focus|. Based on the value of
-  // |tutorial_mode|, a tutorial could be shown, in which case
-  // |profile_path_to_focus| is ignored.
-  static void Show(const base::FilePath& profile_path_to_focus,
-                   profiles::UserManagerTutorialMode tutorial_mode);
-
-  // Hide the User Manager.
-  static void Hide();
-
-  // Returns whether or not the User Manager is showing.
-  static bool IsShowing();
-
   // Called by the cocoa window controller when its window closes and the
   // controller destroyed itself. Deletes the instance.
   void WindowWasClosed();
 
- private:
-  explicit UserManagerMac(Profile* profile);
-  virtual ~UserManagerMac();
-
   // Creates a new UserManagerMac instance for the |guest_profile| and
   // shows the |url|.
   static void OnGuestProfileCreated(Profile* guest_profile,
                                     const std::string& url);
-
-  // 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 UserManagerMac* instance_;  // Weak.
+ private:
+  explicit UserManagerMac(Profile* profile);
+  virtual ~UserManagerMac();
 
   // Controller of the window.
   base::scoped_nsobject<UserManagerWindowController> window_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(UserManagerMac);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_PROFILES_USER_MANAGER_MAC_H_