[Mac] Check for guest mode correctly before opening the user manager.

chrome/browser/ui/cocoa/browser/profile_chooser_controller.mm

Index: chrome/browser/ui/cocoa/browser/profile_chooser_controller.mm
diff --git a/chrome/browser/ui/cocoa/browser/profile_chooser_controller.mm b/chrome/browser/ui/cocoa/browser/profile_chooser_controller.mm
index 739f3a69bf05e4bfa5dcafc70c719ef9e13c2e6d..7676a7574c2c4bb8503bb59cd94b4cb4e2e2e188 100644
--- a/chrome/browser/ui/cocoa/browser/profile_chooser_controller.mm
+++ b/chrome/browser/ui/cocoa/browser/profile_chooser_controller.mm
@@ -212,8 +212,7 @@ class ActiveProfileObserverBridge : public AvatarMenuObserver,
 - (IBAction)showUserManager:(id)sender {
   // Only non-guest users appear in the User Manager.
   base::FilePath profile_path;
-  // The button tag indicates whether the active profile is a non-guest profile.
-  if ([sender tag]) {
+  if (!isGuestSession_) {
     size_t active_index = avatarMenu_->GetActiveProfileIndex();
     profile_path = avatarMenu_->GetItemAt(active_index).profile_path;
   }