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,

[Alexei Svitkine (slow), 2014/09/18 20:54:04]

This is a very strange name for a method when looking at this class definition
by itself.

If it were just a method in the anon namespace used within a single .cc file,
I'd be okay with it, but in a .h file, I think it should have a better name
(i.e. one that matches the comment above it).

However, I'm also somewhat confused by this whole set up. If this is the only
way to create this class, then how does it work for non-guest profiles? (Since
the constructor is private.)

Maybe add a comment at the top of the class to better explain the class (e.g.
its singleton-ish nature and so forth).

[Mike Lerman, 2014/09/19 15:49:30]

Comment added.

The UserManager always operates as the Guest Profile, the profile from which you
launched it becomes Last Active.

                                     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.
+  UserManagerWindowController* get_window_controller() {

[Alexei Svitkine (slow), 2014/09/18 20:54:04]

Remove get_ prefixed, it's used for non-trivial methods (e.g.
GetWindowController), while trivial ones should omit it.

[Mike Lerman, 2014/09/19 15:49:30]

Done.

+    return window_controller_.get();
+  }
+
+ 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_