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..6fe9739cfe52056be72d26220d9b674b39c99607 100644
--- a/chrome/browser/ui/views/profiles/user_manager_view.h
+++ b/chrome/browser/ui/views/profiles/user_manager_view.h
@@ -22,9 +22,11 @@ class UserManagerView : public views::DialogDelegateView {
   // 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.
+  // |profile_path_to_focus| is ignored. After a profile is opened, execute the
+  // |profile_open_action|.
   static void Show(const base::FilePath& profile_path_to_focus,

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

Nit: I'd eliminate these three public statics and have the UserManager function
implementations in the .cc file just do the necessary bits.  This will require
making more things in UserManagerView public or adding accessors (or,
alternately, declaring UserManager a friend), but it eliminates boilerplate and
avoids the possibility of the UserManager and UserManagerView APIs getting out
of sync.

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

In the interest of keeping private things private (like instance_) what do you
think of having UserManagerView and UserManagerMac inherit from
c/b/ui/UserManager, and then I can bring the implementations of the *View and
*Mac methods inside the static methods without having to change the visibility
of the private members? You had implied you preferred to avoid explicit
references from UMView and UMMac to the UserManager, but I think this provides a
good reason to create that dependency.

[Peter Kasting, 2014/09/17 20:14:13]

I don't know if I understand your plan.  Perhaps you could partially implement
it (e.g. implement the views side) so I could see what it consists of?

[Mike Lerman, 2014/09/18 18:32:45]

Couldn't find a great approach. I eliminated these three public statics and had
the UserManager implementations do the necessary bits, as you had suggested.

-                   profiles::UserManagerTutorialMode tutorial_mode);
+                   profiles::UserManagerTutorialMode tutorial_mode,
+                   profiles::UserManagerProfileSelected profile_open_action);
 
   // Hide the User Manager.
   static void Hide();