Make the user manager UI not permit guest mode when preferences dictate

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 485016214c0ad4f49680b449844dc7de05dd1cd4..c8104f767934026b1f38cad2b6f9dca25e9876b5 100644
--- a/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
+++ b/chrome/browser/ui/webui/signin/user_manager_screen_handler.cc
@@ -144,6 +144,12 @@ extensions::ScreenlockPrivateEventRouter* GetScreenlockRouter(
       profile);
 }
 
+bool IsGuestModeEnabled() {
+  PrefService* service = g_browser_process->local_state();
+  DCHECK(service);
+  return service->GetBoolean(prefs::kBrowserGuestModeEnabled);
+}
+
 }  // namespace
 
 // ProfileUpdateObserver ------------------------------------------------------
@@ -280,7 +286,8 @@ void UserManagerScreenHandler::Unlock(const std::string& user_email) {
 
 void UserManagerScreenHandler::HandleInitialize(const base::ListValue* args) {
   SendUserList();
-  web_ui()->CallJavascriptFunction("cr.ui.Oobe.showUserManagerScreen");
+  web_ui()->CallJavascriptFunction("cr.ui.Oobe.showUserManagerScreen",
+      base::FundamentalValue(IsGuestModeEnabled()));
   desktop_type_ = chrome::GetHostDesktopTypeForNativeView(
       web_ui()->GetWebContents()->GetNativeView());
 
@@ -368,9 +375,15 @@ void UserManagerScreenHandler::HandleRemoveUser(const base::ListValue* args) {
 }
 
 void UserManagerScreenHandler::HandleLaunchGuest(const base::ListValue* args) {
-  profiles::SwitchToGuestProfile(desktop_type_,
-                                 base::Bind(&OnSwitchToProfileComplete));
-  ProfileMetrics::LogProfileSwitchUser(ProfileMetrics::SWITCH_PROFILE_GUEST);
+  if (IsGuestModeEnabled()) {
+    profiles::SwitchToGuestProfile(desktop_type_,
+                                   base::Bind(&OnSwitchToProfileComplete));
+    ProfileMetrics::LogProfileSwitchUser(ProfileMetrics::SWITCH_PROFILE_GUEST);
+  } else {
+    // The UI should have prevented the user from allowing the selection of
+    // guest mode.
+    NOTREACHED();
+  }
 }
 
 void UserManagerScreenHandler::HandleLaunchUser(const base::ListValue* args) {
@@ -624,7 +637,7 @@ void UserManagerScreenHandler::SendUserList() {
   }
 
   web_ui()->CallJavascriptFunction("login.AccountPickerScreen.loadUsers",
-    users_list, base::FundamentalValue(true));
+      users_list, base::FundamentalValue(IsGuestModeEnabled()));
 }
 
 void UserManagerScreenHandler::ReportAuthenticationResult(