Fix "Set pages" drop crash by changing outside drags to simply add a new URL

chrome/browser/resources/options/browser_options_startup_page_list.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('options.browser_options', function() {
   /** @const */ var AutocompleteList = cr.ui.AutocompleteList;
   /** @const */ var InlineEditableItem = options.InlineEditableItem;
   /** @const */ var InlineEditableItemList = options.InlineEditableItemList;
 
   /**
@@ skipping 228 matching lines @@
         return;
       }
 
       this.hideDropMarker_();
 
       // Insert the selection at the new position.
       var newIndex = this.dataModel.indexOf(dropTarget.pageInfo_);
       if (this.dropPos == 'below')
         newIndex += 1;
 
-      chrome.send('dragDropStartupPage',
-                  [newIndex, this.selectionModel.selectedIndexes]);
+      // If there are selected indexes, it was a re-order.
+      if (this.selectionModel.selectedIndexes.length > 0) {
+        chrome.send('dragDropStartupPage',
+                    [newIndex, this.selectionModel.selectedIndexes]);
+        return;
+      }
+
+      // Otherwise it was potentially a drop of new data (e.g. a bookmark).
+      var url = e.dataTransfer.getData('url');
+      if (url) {
+        e.preventDefault();
+        chrome.send('addStartupPage', [url, newIndex]);
+      }
     },
 
     /**
      * Handles the dragleave event.
      * @param {Event} e The dragleave event.
      * @private
      */
     handleDragLeave_: function(e) {
       this.hideDropMarker_();
     },
@@ skipping 40 matching lines @@
       this.hideDropMarkerTimer_ = window.setTimeout(function() {
         $('startupPagesListDropmarker').style.display = '';
       }, 100);
     },
   };
 
   return {
     StartupPageList: StartupPageList
   };
 });