MD Settings: On Startup, extract dialog to its own file.

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

 // Copyright 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/settings_startup_pages_handler.h"
 
 #include <string>
 #include <vector>
 
 #include "chrome/browser/prefs/session_startup_pref.h"
@@ skipping 63 matching lines @@
 
 void StartupPagesHandler::OnItemsAdded(int start, int length) {
   OnModelChanged();
 }
 
 void StartupPagesHandler::OnItemsRemoved(int start, int length) {
   OnModelChanged();
 }
 
 void StartupPagesHandler::HandleAddStartupPage(const base::ListValue* args) {
+  CHECK_EQ(2U, args->GetSize());
+
+  const base::Value* callback_id;
+  CHECK(args->Get(0, &callback_id));
+
   std::string url_string;
-  if (!args->GetString(0, &url_string)) {
-    NOTREACHED();
+  CHECK(args->GetString(1, &url_string));
+
+  GURL url;
+  if (!settings_utils::FixupAndValidateStartupPage(url_string, &url)) {
+    ResolveJavascriptCallback(*callback_id, base::FundamentalValue(false));
     return;
   }
 
-  GURL url;
-  if (!settings_utils::FixupAndValidateStartupPage(url_string, &url)) {
-    NOTREACHED();
-    return;
-  }
-
   int row_count = startup_custom_pages_table_model_.RowCount();
   int index;
   if (!args->GetInteger(1, &index) || index > row_count)
     index = row_count;
 
   startup_custom_pages_table_model_.Add(index, url);
   SaveStartupPagesPref();
+  ResolveJavascriptCallback(*callback_id, base::FundamentalValue(true));
 }
 
 void StartupPagesHandler::HandleOnStartupPrefsPageLoad(
     const base::ListValue* args) {
   startup_custom_pages_table_model_.SetObserver(this);
 
   PrefService* prefService = Profile::FromWebUI(web_ui())->GetPrefs();
   SessionStartupPref pref = SessionStartupPref::GetStartupPref(
       prefService);
   startup_custom_pages_table_model_.SetURLs(pref.urls);
@@ skipping 63 matching lines @@
 
 void StartupPagesHandler::UpdateStartupPages() {
   const SessionStartupPref startup_pref = SessionStartupPref::GetStartupPref(
       Profile::FromWebUI(web_ui())->GetPrefs());
   startup_custom_pages_table_model_.SetURLs(startup_pref.urls);
   // The change will go to the JS code in the
   // StartupPagesHandler::OnModelChanged() method.
 }
 
 }  // namespace settings