Add script files of the separated Gallery.app.

chrome/browser/resources/gallery/js/image_editor/image_encoder.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.
 
 'use strict';
 
 /**
  * A namespace class for image encoding functions. All methods are static.
  */
 function ImageEncoder() {}
@@ skipping 208 matching lines @@
     findInsertionRange = function(encodedImage) { return {from: 0, to: 0} };
 
 /**
  * Return serialized metadata ready to write to an image file.
  * The return type is optimized for passing to Blob.append.
  * @return {ArrayBuffer} // TODO(JSDOC).
  */
 ImageEncoder.MetadataEncoder.prototype.encode = function() {
   return new Uint8Array(0).buffer;
 };