Introduce apps API target in //apps and move app.runtime API into it

chrome/common/extensions/api/app_runtime.idl

-// Copyright (c) 2012 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.
-
-// Use the <code>chrome.app.runtime</code> API to manage the app lifecycle.
-// The app runtime manages app installation, controls the event page, and can
-// shut down the app at anytime.
-namespace app.runtime {
-
-  [inline_doc] dictionary LaunchItem {
-    // FileEntry for the file.
-    [instanceOf=FileEntry] object entry;
-
-    // The MIME type of the file.
-    DOMString type;
-  };
-
-  // Optional data for the launch. Either <code>items</code>, or
-  // the pair (<code>url, referrerUrl</code>) can be present for any given
-  // launch.
-  [inline_doc] dictionary LaunchData {
-    // The ID of the file or URL handler that the app is being invoked with.
-    // Handler IDs are the top-level keys in the <code>file_handlers</code>
-    // and/or <code>url_handlers</code> dictionaries in the manifest.
-    DOMString? id;
-
-    // The file entries for the <code>onLaunched</code> event triggered by a
-    // matching file handler in the <code>file_handlers</code> manifest key.
-    LaunchItem[]? items;
-
-    // The URL for the <code>onLaunched</code> event triggered by a matching
-    // URL handler in the <code>url_handlers</code> manifest key.
-    DOMString? url;
-
-    // The referrer URL for the <code>onLaunched</code> event triggered by a
-    // matching URL handler in the <code>url_handlers</code> manifest key.
-    DOMString? referrerUrl;
-
-    // Whether the app is being launched in a <a
-    // href="https://support.google.com/chromebook/answer/3134673">Chrome OS
-    // kiosk session</a>.
-    boolean? isKioskSession;
-  };
-
-  interface Events {
-    // Fired when an app is launched from the launcher.
-    static void onLaunched(optional LaunchData launchData);
-
-    // Fired at Chrome startup to apps that were running when Chrome last shut
-    // down.
-    static void onRestarted();
-  };
-};