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

chrome/browser/ui/user_manager.h

+// Copyright (c) 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_USER_MANAGER_H_
+#define CHROME_BROWSER_UI_USER_MANAGER_H_
+
+#include "chrome/browser/profiles/profile_window.h"
+
+namespace base {
+class FilePath;
+}
+
+// Cross-platform methods for displaying the user manager.
+class UserManager {
+ 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

[Peter Kasting, 2014/09/15 20:17:28]

Since various callers pass an empty FilePath, you should probably note that
that's legal and what it does.

[Mike Lerman, 2014/09/17 18:31:45]

Done.

+  // |tutorial_mode|, a tutorial could be shown, in which case
+  // |profile_path_to_focus| is ignored. After a profile is opened, execute the

[Peter Kasting, 2014/09/15 20:17:28]

Nit: execute -> executes

[Mike Lerman, 2014/09/17 18:31:46]

Done.

+  // |profile_open_action|.
+  static void Show(const base::FilePath& profile_path_to_focus,
+                   profiles::UserManagerTutorialMode tutorial_mode,
+                   profiles::UserManagerProfileSelected profile_open_action);
+
+  // Hide the User Manager.

[Peter Kasting, 2014/09/15 20:17:28]

Nit: Hide -> Hides

[Mike Lerman, 2014/09/17 18:31:46]

Done.

+  static void Hide();
+
+  // Returns whether or not the User Manager is showing.

[Peter Kasting, 2014/09/15 20:17:27]

Nit: Remove "or not"

[Mike Lerman, 2014/09/17 18:31:45]

Done.

+  static bool IsShowing();
+};
+
+#endif  // CHROME_BROWSER_UI_USER_MANAGER_H_