MD Settings: Fix Appearance home page URL crash

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

 // Copyright 2016 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/on_startup_handler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "chrome/browser/extensions/settings_api_helpers.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/webui/settings_utils.h"
 #include "content/public/browser/web_ui.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/management_policy.h"
 #include "extensions/common/extension.h"
 
 namespace settings {
 
 OnStartupHandler::OnStartupHandler() {}
 OnStartupHandler::~OnStartupHandler() {}
 
 void OnStartupHandler::RegisterMessages() {
   web_ui()->RegisterMessageCallback(
       "getNtpExtension", base::Bind(&OnStartupHandler::HandleGetNtpExtension,
                                     base::Unretained(this)));
+  web_ui()->RegisterMessageCallback(
+      "validateStartupPage",
+      base::Bind(&OnStartupHandler::HandleValidateStartupPage,
+                 base::Unretained(this)));
 }
 
 void OnStartupHandler::HandleGetNtpExtension(const base::ListValue* args) {
   const base::Value* callback_id;
   CHECK(args->Get(0, &callback_id));
 
   AllowJavascript();
 
   Profile* profile = Profile::FromWebUI(web_ui());
   const extensions::Extension* ntp_extension =
       extensions::GetExtensionOverridingNewTabPage(profile);
 
   if (!ntp_extension) {
     ResolveJavascriptCallback(*callback_id, *base::Value::CreateNullValue());
     return;
   }
 
   base::DictionaryValue dict;
   dict.SetString("id", ntp_extension->id());
   dict.SetString("name", ntp_extension->name());
   dict.SetBoolean("canBeDisabled",
                   !extensions::ExtensionSystem::Get(profile)
                        ->management_policy()
                        ->MustRemainEnabled(ntp_extension, nullptr));
   ResolveJavascriptCallback(*callback_id, dict);
 }
 
+void OnStartupHandler::HandleValidateStartupPage(const base::ListValue* args) {
+  AllowJavascript();
+
+  CHECK_EQ(args->GetSize(), 2U);
+
+  const base::Value* callback_id;
+  CHECK(args->Get(0, &callback_id));
+
+  std::string url_string;
+  CHECK(args->GetString(1, &url_string));
+
+  bool valid = settings_utils::FixupAndValidateStartupPage(url_string, nullptr);
+  ResolveJavascriptCallback(*callback_id, base::Value(valid));
+}
+
 }  // namespace settings