Typecheck JS files for chrome://help before doing import transition

chrome/browser/resources/uber/uber.js

 // 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.
 
 cr.define('uber', function() {
   /**
    * Options for how web history should be handled.
    */
   var HISTORY_STATE_OPTION = {
     PUSH: 1,    // Push a new history state.
@@ skipping 131 matching lines @@
    *  { method : "methodToInvoke",
    *    params : {...}
    *  }
    *
    * |method| is required, while |params| is optional. Extra parameters required
    * by a method must be specified by that method's documentation.
    *
    * @param {Event} e The posted object.
    */
   function handleWindowMessage(e) {
+    e = /** @type{!MessageEvent.<!{method: string, params: *}>} */ (e);

[Dan Beam, 2014/07/23 22:09:24]

we should stay consistent regarding

  /** @type {T} */(t)
            
vs.

  /** @type {T} */ (t)
                  ^
i'm in favor of no space

[Vitaly Pavlenko, 2014/07/24 01:09:31]

Done.

     if (e.data.method === 'beginInterceptingEvents') {
       backgroundNavigation();
     } else if (e.data.method === 'stopInterceptingEvents') {
       foregroundNavigation();
     } else if (e.data.method === 'ready') {
       pageReady(e.origin);
     } else if (e.data.method === 'updateHistory') {
       updateHistory(e.origin, e.data.params.state, e.data.params.path,
                     e.data.params.replace);
     } else if (e.data.method === 'setTitle') {
       setTitle(e.origin, e.data.params.title);
     } else if (e.data.method === 'showPage') {
       showPage(e.data.params.pageId,
                HISTORY_STATE_OPTION.PUSH,
                e.data.params.path);
     } else if (e.data.method === 'navigationControlsLoaded') {
       onNavigationControlsLoaded();
     } else if (e.data.method === 'adjustToScroll') {
-      adjustToScroll(e.data.params);
+      adjustToScroll(/** @type {number} */(e.data.params));
     } else if (e.data.method === 'mouseWheel') {
-      forwardMouseWheel(e.data.params);
+      forwardMouseWheel(/** @type {Object} */(e.data.params));
     } else {
       console.error('Received unexpected message', e.data);
     }
   }
 
   /**
    * Sends the navigation iframe to the background.
    */
   function backgroundNavigation() {
     navFrame.classList.add('background');
@@ skipping 21 matching lines @@
     if (isRTL()) {
       uber.invokeMethodOnWindow(navFrame.firstChild.contentWindow,
                                 'setContentChanging',
                                 enabled);
     }
   }
 
   /**
    * Get an iframe based on the origin of a received post message.
    * @param {string} origin The origin of a post message.
-   * @return {!HTMLElement} The frame associated to |origin| or null.
+   * @return {!Element} The frame associated to |origin| or null.
    */
   function getIframeFromOrigin(origin) {
     assert(origin.substr(-1) != '/', 'invalid origin given');
     var query = '.iframe-container > iframe[src^="' + origin + '/"]';
-    return document.querySelector(query);
+    var element = document.querySelector(query);
+    assert(element, 'expected an element');
+    return /** @type {!Element} */ (element);
   }
 
   /**
    * Changes the path past the page title (i.e. chrome://chrome/settings/(.*)).
    * @param {Object} state The page's state object for the navigation.
    * @param {string} path The new /path/ to be set after the page name.
    * @param {number} historyOption The type of history modification to make.
    */
   function changePathTo(state, path, historyOption) {
     assert(!path || path.substr(-1) != '/', 'invalid path given');
@@ skipping 76 matching lines @@
     var queue = queuedInvokes[container.id] || [];
     queuedInvokes[container.id] = undefined;
     for (var i = 0; i < queue.length; i++) {
       uber.invokeMethodOnWindow(frame.contentWindow, queue[i][0], queue[i][1]);
     }
   }
 
   /**
    * Selects and navigates a subpage. This is called from uber-frame.
    * @param {string} pageId Should match an id of one of the iframe containers.
-   * @param {integer} historyOption Indicates whether we should push or replace
+   * @param {number} historyOption Indicates whether we should push or replace
    *     browser history.
    * @param {string} path A sub-page path.
    */
   function showPage(pageId, historyOption, path) {
     var container = $(pageId);
 
     // Lazy load of iframe contents.
     var sourceUrl = container.dataset.url + (path || '');
     var frame = container.querySelector('iframe');
     if (!frame) {
@@ skipping 37 matching lines @@
     adjustToScroll(0);
 
     var selectedFrame = getSelectedIframe().querySelector('iframe');
     uber.invokeMethodOnWindow(selectedFrame.contentWindow, 'frameSelected');
 
     if (historyOption != HISTORY_STATE_OPTION.NONE)
       changePathTo({}, path, historyOption);
 
     if (container.dataset.title)
       document.title = container.dataset.title;
-    $('favicon').href = 'chrome://theme/' + container.dataset.favicon;
-    $('favicon2x').href = 'chrome://theme/' + container.dataset.favicon + '@2x';
+    assert('favicon' in container.dataset);
+
+    var dataset = /** @type {{favicon: string}} */ (container.dataset);
+    $('favicon').href = 'chrome://theme/' + dataset.favicon;
+    $('favicon2x').href = 'chrome://theme/' + dataset.favicon + '@2x';
 
     updateNavigationControls();
   }
 
   function onNavigationControlsLoaded() {
     updateNavigationControls();
   }
 
   /**
    * Sends a message to uber-frame to update the appearance of the nav controls.
@@ skipping 60 matching lines @@
   }
 
   return {
     onLoad: onLoad,
     onPopHistoryState: onPopHistoryState
   };
 });
 
 window.addEventListener('popstate', uber.onPopHistoryState);
 document.addEventListener('DOMContentLoaded', uber.onLoad);