Prevent dragging in open/save dialogs.

chrome/browser/resources/file_manager/js/file_transfer_controller.js

Index: chrome/browser/resources/file_manager/js/file_transfer_controller.js
diff --git a/chrome/browser/resources/file_manager/js/file_transfer_controller.js b/chrome/browser/resources/file_manager/js/file_transfer_controller.js
index dc07b1bf782f90026d24b0746050839cfe753aca..e81219931c4697431d83422b01574a33d8aa0fed 100644
--- a/chrome/browser/resources/file_manager/js/file_transfer_controller.js
+++ b/chrome/browser/resources/file_manager/js/file_transfer_controller.js
@@ -39,6 +39,7 @@ FileTransferController.prototype = {
    * @param {cr.ui.List} list Items in the list will be draggable.
    */
   attachDragSource: function(list) {
+    list.style.webkitUserDrag = 'element';
     list.addEventListener('dragstart', this.onDragStart_.bind(this, list));
     list.addEventListener('dragend', this.onDragEnd_.bind(this, list));
     list.addEventListener('drag', this.onDrag_.bind(this, list));