Fix file manager to better handle missing roots and scan failure

chrome/browser/resources/file_manager/js/directory_model.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.
 
 // If directory files changes too often, don't rescan directory more than once
 // per specified interval
 const SIMULTANEOUS_RESCAN_INTERVAL = 1000;
 
 /**
  * Data model of the file manager.
@@ skipping 312 matching lines @@
     this.selectedNames = selectedNames;
     this.fileListSelection_.leadIndex = leadIndex;
     this.leadName = leadName;
     this.fileListSelection_.endChange();
     cr.dispatchSimpleEvent(this, 'end-update-files');
   },
 
   /**
    * Cancels waiting and scheduled rescans and starts new scan.
    *
-   * @param {Function} callback Called when scan completed.
+   * If the scan completes successfully on the first attempt, the callback will
+   * be invoked and a 'scan-completed' event will be dispatched.  If the scan
+   * fails for any reason, we'll periodically retry until it succeeds (and then
+   * send a 'rescan-complete' event) or is cancelled or replaced by another
+   * scan.
+   *
+   * @param {Function} callback Called if scan completes on the first attempt.
+   *   Note that this will NOT be called if the scan fails but later succeeds.
    */
   scan_: function(callback) {
     if (this.rescanTimeout_) {
       clearTimeout(this.rescanTimeout_);
       this.rescanTimeout_ = 0;
     }
     if (this.runningScan_)
       this.runningScan_.cancel();
     this.pendingScan_ = null;
 
@@ skipping 146 matching lines @@
   },
 
   /**
    * Change the current directory to the directory represented by a
    * DirectoryEntry.
    *
    * Dispatches the 'directory-changed' event when the directory is successfully
    * changed.
    *
    * @param {DirectoryEntry} dirEntry The absolute path to the new directory.
-   * @param {function} action Action executed when the directory loaded.
-   *                              By default selects the first item
-   *                              (unless it's a save dialog).
+   * @param {function} action Action executed if the directory loads
+   *    successfully.  By default selects the first item (unless it's a save
+   *    dialog).
    * @param {boolean} initial True if it comes from setupPath and
    *                          false if caused by an user action.
    */
   changeDirectoryEntry_: function(dirEntry, action, initial) {
     var current = this.currentEntry;
     this.currentDirEntry_ = dirEntry;
     function onRescanComplete() {
       action();
       // For tests that open the dialog to empty directories, everything
       // is loaded at this point.
       chrome.test.sendMessage('directory-change-complete');
     }
     this.updateRootsListSelection_();
     this.scan_(onRescanComplete);
 
     var e = new cr.Event('directory-changed');
     e.previousDirEntry = this.currentEntry;
     e.newDirEntry = dirEntry;
     e.initial = initial;
     this.dispatchEvent(e);
   },
 
   /**
    * Change the state of the model to reflect the specified path (either a
    * file or directory).
    *
    * @param {string} path The root path to use
    * @param {Function=} opt_loadedCallback Invoked when the entire directory
-   *     has been loaded and any default file selected.
+   *     has been loaded and any default file selected.  If there are any
+   *     errors loading the directory this will not get called (even if the
+   *     directory loads OK on retry later).
    * @param {Function=} opt_pathResolveCallback Invoked as soon as the path has
    *     been resolved, and called with the base and leaf portions of the path
    *     name, and a flag indicating if the entry exists.
    */
   setupPath: function(path, opt_loadedCallback, opt_pathResolveCallback) {
     // Split the dirname from the basename.
     var ary = path.match(/^(?:(.*)\/)?([^\/]*)$/);
     var autoSelect = function() {
           this.selectIndex(this.autoSelectIndex_);
           if (opt_loadedCallback)
@@ skipping 48 matching lines @@
     var onBaseError = function(err) {
       resolveCallback(false);
       console.log('Unexpected error resolving default base "' +
                   baseName + '": ' + err);
       if (path != '/' + DirectoryModel.DOWNLOADS_DIRECTORY) {
         // Can't find the provided path, let's go to default one instead.
         this.setupDefaultPath(opt_loadedCallback);
       } else {
         // Well, we can't find the downloads dir. Let's just show something,
         // or we will get an infinite recursion.
-        this.changeDirectory('/', opt_loadedCallback, true);
+        this.changeDirectoryEntry_(this.root_, opt_loadedCallback, true);
       }
     }.bind(this);
 
     var onBaseFound = function(baseDirEntry) {
       if (!leafName) {
         // Default path is just a directory, cd to it and we're done.
         this.changeDirectoryEntry_(baseDirEntry, autoSelect, true);
         return;
       }
 
@@ skipping 316 matching lines @@
 
   recordMetrics_: function() {
     metrics.recordInterval('DirectoryScan');
     if (this.dir_.fullPath ==
         '/' + DirectoryModel.DOWNLOADS_DIRECTORY) {
       metrics.recordMediumCount("DownloadsCount", this.list_.length);
     }
   }
 };