MD Settings: Update some Settings handlers to use new JS lifecycle management.

chrome/browser/ui/webui/settings/appearance_handler.cc

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/settings/appearance_handler.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/values.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/web_ui.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/desktop_background/user_wallpaper_delegate.h"
 #include "ash/shell.h"
 #endif
 
 namespace settings {
 
 AppearanceHandler::AppearanceHandler(content::WebUI* webui)
     : profile_(Profile::FromWebUI(webui)) {
-  registrar_.Add(this, chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
-                 content::Source<ThemeService>(
-                     ThemeServiceFactory::GetForProfile(profile_)));
 }
 
-AppearanceHandler::~AppearanceHandler() {
-  registrar_.RemoveAll();
-}
+AppearanceHandler::~AppearanceHandler() {}
 
 void AppearanceHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback(
       "resetTheme",
       base::Bind(&AppearanceHandler::HandleResetTheme, base::Unretained(this)));
   web_ui()->RegisterMessageCallback(
       "getResetThemeEnabled",
       base::Bind(&AppearanceHandler::HandleGetResetThemeEnabled,
                  base::Unretained(this)));
 #if defined(OS_CHROMEOS)
   web_ui()->RegisterMessageCallback(
       "openWallpaperManager",
       base::Bind(&AppearanceHandler::HandleOpenWallpaperManager,
                  base::Unretained(this)));
 #endif
 }
 
+void AppearanceHandler::OnJavascriptAllowed() {
+  registrar_.Add(this, chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
+                 content::Source<ThemeService>(
+                     ThemeServiceFactory::GetForProfile(profile_)));
+}
+
+void AppearanceHandler::OnJavascriptDisallowed() {
+  registrar_.RemoveAll();
+}
+
 void AppearanceHandler::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
   switch (type) {
     case chrome::NOTIFICATION_BROWSER_THEME_CHANGED: {
-      web_ui()->CallJavascriptFunction(
-          "cr.webUIListenerCallback",
-          base::StringValue("reset-theme-enabled-changed"),
-          base::FundamentalValue(ResetThemeEnabled()));
+      CallJavascriptFunction("cr.webUIListenerCallback",
+                             base::StringValue("reset-theme-enabled-changed"),
+                             base::FundamentalValue(ResetThemeEnabled()));
       break;
     }
     default:
       NOTREACHED();
   }
 }
 
 void AppearanceHandler::HandleResetTheme(const base::ListValue* /*args*/) {
   ThemeServiceFactory::GetForProfile(profile_)->UseDefaultTheme();
 }
 
 bool AppearanceHandler::ResetThemeEnabled() const {
   // TODO(jhawkins): Handle native/system theme button.
   return !ThemeServiceFactory::GetForProfile(profile_)->UsingDefaultTheme();
 }
 
 void AppearanceHandler::HandleGetResetThemeEnabled(
     const base::ListValue* args) {
+  AllowJavascript();
+
   CHECK_EQ(1U, args->GetSize());
   const base::Value* callback_id;
   CHECK(args->Get(0, &callback_id));
   ResolveJavascriptCallback(*callback_id,
                             base::FundamentalValue(ResetThemeEnabled()));
 }
 
 #if defined(OS_CHROMEOS)
 void AppearanceHandler::HandleOpenWallpaperManager(
     const base::ListValue* /*args*/) {
   ash::Shell::GetInstance()->user_wallpaper_delegate()->OpenSetWallpaperPage();
 }
 #endif
 
 }  // namespace settings