MD Settings: break SettingsPageUIHandler to its own file

chrome/browser/ui/webui/settings/settings_page_ui_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/settings_page_ui_handler.h"
+
+#include "content/public/browser/web_ui.h"
+
+namespace settings {
+
+SettingsPageUIHandler::SettingsPageUIHandler() {}
+
+SettingsPageUIHandler::~SettingsPageUIHandler() {}
+
+void SettingsPageUIHandler::ResolveJavascriptCallback(
+    const base::Value& callback_id,
+    const base::Value& response) {
+  // cr.webUIResponse is a global JS function exposed from cr.js.
+  web_ui()->CallJavascriptFunction(
+      "cr.webUIResponse", callback_id,
+      base::FundamentalValue(true), response);
+}
+
+void SettingsPageUIHandler::RejectJavascriptCallback(
+    const base::Value& callback_id,
+    const base::Value& response) {
+  // cr.webUIResponse is a global JS function exposed from cr.js.
+  web_ui()->CallJavascriptFunction(
+      "cr.webUIResponse", callback_id,
+      base::FundamentalValue(false), response);
+}
+
+}  // namespace settings