Settings to control Add Person and Browse as Guest.

chrome/browser/ui/webui/signin/user_manager_screen_handler.cc

Index: chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
diff --git a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
index 8aeffb250ebceceff0364e2aad73cdcb0f1b651f..15bd53382552939e966eb6f4862a12a283b0ff79 100644
--- a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
+++ b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
@@ -150,6 +150,12 @@ bool IsGuestModeEnabled() {
   return service->GetBoolean(prefs::kBrowserGuestModeEnabled);
 }
 
+bool IsAddPersonEnabled() {
+  PrefService* service = g_browser_process->local_state();
+  DCHECK(service);
+  return service->GetBoolean(prefs::kBrowserAddPersonEnabled);
+}
+
 }  // namespace
 
 // ProfileUpdateObserver ------------------------------------------------------
@@ -291,7 +297,8 @@ void UserManagerScreenHandler::Unlock(const std::string& user_email) {
 void UserManagerScreenHandler::HandleInitialize(const base::ListValue* args) {
   SendUserList();
   web_ui()->CallJavascriptFunction("cr.ui.Oobe.showUserManagerScreen",
-      base::FundamentalValue(IsGuestModeEnabled()));
+      base::FundamentalValue(IsGuestModeEnabled()),
+      base::FundamentalValue(IsAddPersonEnabled()));
   desktop_type_ = chrome::GetHostDesktopTypeForNativeView(
       web_ui()->GetWebContents()->GetNativeView());
 
@@ -299,9 +306,15 @@ void UserManagerScreenHandler::HandleInitialize(const base::ListValue* args) {
 }
 
 void UserManagerScreenHandler::HandleAddUser(const base::ListValue* args) {
-  profiles::CreateAndSwitchToNewProfile(desktop_type_,
-                                        base::Bind(&OnSwitchToProfileComplete),
-                                        ProfileMetrics::ADD_NEW_USER_MANAGER);
+  if (IsAddPersonEnabled()) {

[Evan Stade, 2014/08/30 01:15:37]

nit: invert this check and return early

[Mike Lerman, 2014/09/02 16:58:29]

Done.

+    profiles::CreateAndSwitchToNewProfile(
+        desktop_type_,
+        base::Bind(&OnSwitchToProfileComplete),
+        ProfileMetrics::ADD_NEW_USER_MANAGER);
+  } else {
+    // The UI should have prevented the user from adding a user.
+    NOTREACHED();
+  }
 }
 
 void UserManagerScreenHandler::HandleAuthenticatedLaunchUser(