MD Settings: Add dedicated C++ handler for restart/relaunch/powerwash.

chrome/browser/resources/settings/lifetime_browser_proxy.js

+// 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.
+
+cr.define('settings', function() {
+  /** @interface */
+  function LifetimeBrowserProxy() {}
+
+  LifetimeBrowserProxy.prototype = {
+    // Triggers a browser restart.
+    restart: function() {},
+
+    // Triggers a browser relaunch.
+    relaunch: function() {},
+
+<if expr="chromeos">
+    // First signs out current user and then performs a restart.
+    logOutAndRestart: function() {},
+
+    // Triggers a factory reset.
+    factoryReset: function() {},
+</if>
+  };
+
+  /**
+   * @constructor
+   * @implements {settings.LifetimeBrowserProxy}
+   */
+  function LifetimeBrowserProxyImpl() {}
+  cr.addSingletonGetter(LifetimeBrowserProxyImpl);
+
+  LifetimeBrowserProxyImpl.prototype = {
+    /** @override */
+    restart: function() {
+      chrome.send('restart');
+    },
+
+    /** @override */
+    relaunch: function() {
+      chrome.send('relaunch');
+    },
+
+<if expr="chromeos">
+    /** @override */
+    logOutAndRestart: function() {
+      chrome.send('logOutAndRestart');
+    },
+
+    /** @override */
+    factoryReset: function() {
+      chrome.send('factoryReset');
+    },
+</if>
+  };
+
+  return {
+    LifetimeBrowserProxy: LifetimeBrowserProxy,
+    LifetimeBrowserProxyImpl: LifetimeBrowserProxyImpl,
+  };
+});