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

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

Index: chrome/browser/ui/views/profiles/user_manager_view.h
diff --git a/chrome/browser/ui/views/profiles/user_manager_view.h b/chrome/browser/ui/views/profiles/user_manager_view.h
index d9be1d38ae22510560fc0b642544d8682f84f776..a5d0b3172b21913a8458b68b51510464cf2cd340 100644
--- a/chrome/browser/ui/views/profiles/user_manager_view.h
+++ b/chrome/browser/ui/views/profiles/user_manager_view.h
@@ -19,24 +19,8 @@ class WebView;
 // Dialog widget that contains the Desktop User Manager webui.
 class UserManagerView : public views::DialogDelegateView {
  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();
-
- private:
-  friend struct base::DefaultDeleter<UserManagerView>;
-
+  // Do not call directly. To display the User Manager, use UserManager::Show().
   UserManagerView();
-  virtual ~UserManagerView();
 
   // Creates a new UserManagerView instance for the |guest_profile| and
   // shows the |url|.
@@ -45,6 +29,11 @@ class UserManagerView : public views::DialogDelegateView {
                                     Profile* guest_profile,
                                     const std::string& url);
 
+ private:
+  virtual ~UserManagerView();
+
+  friend struct base::DefaultDeleter<UserManagerView>;
+
   // Creates dialog and initializes UI.
   void Init(const base::FilePath& profile_path_to_focus,
             Profile* guest_profile,
@@ -65,9 +54,6 @@ class UserManagerView : public views::DialogDelegateView {
   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);
 };