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

(either ones blocking guest mode in particular or guest mode).

Follow-up to the CL http://codereview.chromium.org/385073008

CL is currently blocked on crbug.com/394413. No more, it landed!

BUG=306322

Review URL: https://codereview.chromium.org/471973003

Cr-Commit-Position: refs/heads/master@{#290069}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290069 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/user_manager/user_manager.js

@@ -34,13 +34,17 @@ cr.define('cr.ui', function() {
    * Shows the given screen.
    * @param {Object} screen Screen params dict, e.g. {id: screenId, data: data}
    */
-  Oobe.showUserManagerScreen = function() {
+  Oobe.showUserManagerScreen = function(showGuest) {
     Oobe.getInstance().showScreen({id: 'account-picker',
                                    data: {disableAddUser: false}});
     // The ChromeOS account-picker will hide the AddUser button if a user is
     // logged in and the screen is "locked", so we must re-enabled it
     $('add-user-header-bar-item').hidden = false;
 
+    // Hide the Guest Mode option if the user is not permitted to select it.
+    $('guest-user-button').hidden = !showGuest;
+    $('login-header-bar').hidden = false;
+
     // Disable the context menu, as the Print/Inspect element items don't
     // make sense when displayed as a widget.
     document.addEventListener('contextmenu', function(e) {e.preventDefault();});
@@ -130,6 +134,10 @@ cr.define('UserManager', function() {
     login.AccountPickerScreen.register();
     cr.ui.Bubble.decorate($('bubble'));
     login.HeaderBar.decorate($('login-header-bar'));
+
+    // Hide the header bar until the showUserManagerMethod can apply function
+    // parameters that affect widget visiblity.
+    $('login-header-bar').hidden = true;
     chrome.send('userManagerInitialize');
   }
 

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(