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

chrome/browser/ui/cocoa/profiles/user_manager_mac.mm

Index: chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
diff --git a/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm b/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
index 957d95ba57bb6b8b04cab3e077f8fa47836a668c..c1497bbb7c4ee80e471a5d15f2d82459beac8c0e 100644
--- a/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
+++ b/chrome/browser/ui/cocoa/profiles/user_manager_mac.mm
@@ -23,23 +23,22 @@
 const int kWindowWidth = 900;
 const int kWindowHeight = 700;
 
-namespace chrome {
-
-// Declared in browser_dialogs.h so others don't have to depend on this header.
-void ShowUserManager(const base::FilePath& profile_path_to_focus) {
-  UserManagerMac::Show(
-      profile_path_to_focus, profiles::USER_MANAGER_NO_TUTORIAL);
-}
-
-void ShowUserManagerWithTutorial(profiles::UserManagerTutorialMode tutorial) {
-  UserManagerMac::Show(base::FilePath(), tutorial);
+void UserManager::Show(
+    const base::FilePath& profile_path_to_focus,
+    profiles::UserManagerTutorialMode tutorial_mode,
+    profiles::UserManagerProfileSelected profile_open_action) {
+  UserManagerMac::Show(profile_path_to_focus,
+                        tutorial_mode,
+                        profile_open_action);
 }
 
-void HideUserManager() {
+void UserManager::Hide() {
   UserManagerMac::Hide();
 }
 
-}  // namespace chrome
+bool UserManager::IsShowing() {
+  return UserManagerMac::IsShowing();
+}
 
 // Custom WebContentsDelegate that allows handling of hotkeys.
 class UserManagerWebContentsDelegate : public content::WebContentsDelegate {
@@ -175,8 +174,10 @@ UserManagerMac::~UserManagerMac() {
 }
 
 // static
-void UserManagerMac::Show(const base::FilePath& profile_path_to_focus,
-                          profiles::UserManagerTutorialMode tutorial_mode) {
+void UserManagerMac::Show(
+    const base::FilePath& profile_path_to_focus,
+    profiles::UserManagerTutorialMode tutorial_mode,
+    profiles::UserManagerProfileSelected profile_open_action) {
   if (instance_) {
     // If there's a user manager window open already, just activate it.
     [instance_->window_controller_ show];
@@ -188,6 +189,7 @@ void UserManagerMac::Show(const base::FilePath& profile_path_to_focus,
   profiles::CreateGuestProfileForUserManager(
       profile_path_to_focus,
       tutorial_mode,
+      profile_open_action,
       base::Bind(&UserManagerMac::OnGuestProfileCreated));
 }