[filemanager] Fix exception when selecting the Drive root in open-folder dialog.

chrome/browser/resources/file_manager/js/file_manager.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.
 
 /**
  * FileManager constructor.
  *
  * FileManager objects encapsulate the functionality of the file selector
  * dialogs, as well as the full screen file manager application (though the
  * latter is not yet implemented).
  *
  * @constructor
  * @param {HTMLElement} dialogDom The DOM node containing the prototypical
  *     dialog UI.
  */
 function FileManager(dialogDom) {
   this.dialogDom_ = dialogDom;
   this.filesystem_ = null;
   this.params_ = location.search ?
                  JSON.parse(decodeURIComponent(location.search.substr(1))) :
                  {};
+  if (this.params_.defaultPath && this.params_.defaultPath.indexOf('/') != 0)
+    this.params_.defaultPath = '/' + this.params_.defaultPath;
 
   this.listType_ = null;
   this.showDelayTimeout_ = null;
 
   this.selection = null;
 
   this.butterTimer_ = null;
   this.currentButter_ = null;
   this.butterLastShowTime_ = 0;
 
@@ skipping 4167 matching lines @@
       if (cancelled) return;
       cleanup();
       selection.urls = resolvedUrls;
       // Call next method on a timeout, as it's unsafe to
       // close a window from a callback.
       setTimeout(this.callSelectFilesApiAndClose_.bind(this, selection), 0);
     }.bind(this);
 
     var onProperties = function(properties) {
       for (var i = 0; i < properties.length; i++) {
-        if (properties[i].present) {
+        if (!properties[i] || properties[i].present) {
           // For files already in GCache, we don't get any transfer updates.
           filesTotal--;
         }
       }
       this.resolveSelectResults_(selection.urls, onResolved);
     }.bind(this);
 
     setup();
     this.metadataCache_.get(selection.urls, 'gdata', onProperties);
   };
@@ skipping 420 matching lines @@
     function closeBanner() {
       self.cleanupGDataWelcome_();
       // Stop showing the welcome banner.
       localStorage[WELCOME_HEADER_COUNTER_KEY] = WELCOME_HEADER_COUNTER_LIMIT;
     }
 
     return maybeShowBanner;
   };
 })();