Adds animation on a hovered directory/volume when dragging files in Files.app

chrome/browser/resources/file_manager/js/file_transfer_controller.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.
 
 /**
  * Global (placed in the window object) variable name to hold internal
  * file dragging information. Needed to show visual feedback while dragging
  * since DataTransfer object is in protected state. Reachable from other
  * file manager instances.
  */
@@ skipping 406 matching lines @@
     event.preventDefault();
     this.paste(event.dataTransfer, destinationPath,
                this.selectDropEffect_(event, destinationPath));
     this.setDropTarget_(null);
   },
 
   /**
    * @this {FileTransferController}
    */
   setDropTarget_: function(domElement, isDirectory, opt_dataTransfer,
                            opt_destinationPath) {

[yoshiki, 2013/03/08 08:10:38]

Could you add @param annotations?

[mtomasz, 2013/03/11 03:17:50]

Done.

     if (this.dropTarget_ == domElement)
       return;
 
     /** @type {string?} */
     this.destinationPath_ = null;
     if (domElement) {
       if (isDirectory &&
           this.canPasteOrDrop_(opt_dataTransfer, opt_destinationPath)) {

[yoshiki, 2013/03/08 08:10:38]

The first argument of |canPasteOrDrop_| seems not to accept undefined. But
|opt_dataTransfer| may be undefined. Should you add undefined-check?

[mtomasz, 2013/03/11 03:17:50]

Done.

         domElement.classList.add('accepts');
         this.destinationPath_ = opt_destinationPath;
       }
     }
     if (this.dropTarget_ && this.dropTarget_.classList.contains('accepts')) {
       var oldDropTarget = this.dropTarget_;
       var self = this;
       setTimeout(function() {
         if (oldDropTarget != self.dropTarget_)
           oldDropTarget.classList.remove('accepts');
       }, 0);
     }
     this.dropTarget_ = domElement;
     if (this.navigateTimer_ !== undefined) {
       clearTimeout(this.navigateTimer_);
       this.navigateTimer_ = undefined;
     }
-    if (domElement && isDirectory && opt_destinationPath) {
+    if (domElement && isDirectory && opt_destinationPath &&
+        this.canPasteOrDrop_(opt_dataTransfer, opt_destinationPath)) {

[yoshiki, 2013/03/08 08:10:38]

ditto.

[mtomasz, 2013/03/11 03:17:50]

Done.

       this.navigateTimer_ = setTimeout(function() {
         this.directoryModel_.changeDirectory(opt_destinationPath);
       }.bind(this), 2000);
     }
   },
 
   /**
    * @this {FileTransferController}
    * @return {boolean} Returns false if {@code <input type="text">} element is
    *     currently active. Otherwise, returns true.
@@ skipping 102 matching lines @@
       return;
     // queryCommandEnabled returns true if event.returnValue is false.
     event.returnValue = !this.canPasteOrDrop_(event.clipboardData);
   },
 
   /**
    * @this {FileTransferController}
    * @return {boolean}  Returns true if {@code opt_destinationPath} is
    *     available to be pasted to. Otherwise, returns false.
    */
   canPasteOrDrop_: function(dataTransfer, opt_destinationPath) {

[yoshiki, 2013/03/08 08:10:38]

Could you add @param annotations?

[mtomasz, 2013/03/11 03:17:50]

Done.

     var destinationPath = opt_destinationPath ||
                           this.directoryModel_.getCurrentDirPath();
     if (this.directoryModel_.isPathReadOnly(destinationPath)) {
       return false;
     }
     if (this.directoryModel_.isSearching())
       return false;
 
     if (!dataTransfer.types || dataTransfer.types.indexOf('fs/tag') == -1)
       return false;  // Unsupported type of content.
@@ skipping 176 matching lines @@
         !event.ctrlKey) {
       return 'move';
     }
     if (event.dataTransfer.effectAllowed == 'copyMove' &&
         event.shiftKey) {
       return 'move';
     }
     return 'copy';
   },
 };