[Files app] ES6 class for content_metadata_provider.js

Bug: 778674
Change-Id: Ic0e6c4588bb7258a87d7817196ef554591e62e22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647642
Commit-Queue: François Degros <fdegros@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Auto-Submit: François Degros <fdegros@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666614}

ui/file_manager/file_manager/foreground/js/metadata/content_metadata_provider.js

@@ -2,15 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/**
+/** @final */
+class ContentMetadataProvider extends MetadataProvider {
+  /**
    * @param {!MessagePort=} opt_messagePort Message port overriding the default
    *     worker port.
- * @extends {MetadataProvider}
- * @constructor
- * @struct
    */
-function ContentMetadataProvider(opt_messagePort) {
-  MetadataProvider.call(this, ContentMetadataProvider.PROPERTY_NAMES);
+  constructor(opt_messagePort) {
+    super(ContentMetadataProvider.PROPERTY_NAMES);
 
     /**
      * Pass all URLs to the metadata reader until we have a correct filter.
@@ -18,10 +17,7 @@ function ContentMetadataProvider(opt_messagePort) {
      */
     this.urlFilter_ = /.*/;
 
-  /**
-   * @private {!MessagePort}
-   * @const
-   */
+    /** @private @const {!MessagePort} */
     this.dispatcher_ = opt_messagePort ?
         opt_messagePort :
         new SharedWorker(ContentMetadataProvider.WORKER_SCRIPT).port;
@@ -38,48 +34,19 @@ function ContentMetadataProvider(opt_messagePort) {
 
     /**
      * Map from Entry.toURL() to callback.
-   * Note that simultaneous requests for same url are handled in MetadataCache.
-   * @private {!Object<!string, !Array<function(!MetadataItem)>>}
-   * @const
+     * Note that simultaneous requests for same url are handled in
+     * MetadataCache.
+     * @private @const {!Object<!string, !Array<function(!MetadataItem)>>}
      */
     this.callbacks_ = {};
-}
-
-/**
- * @const {!Array<string>}
- */
-ContentMetadataProvider.PROPERTY_NAMES = [
-  'contentImageTransform',
-  'contentThumbnailTransform',
-  'contentThumbnailUrl',
-  'exifLittleEndian',
-  'ifd',
-  'imageHeight',
-  'imageWidth',
-  'mediaAlbum',
-  'mediaArtist',
-  'mediaDuration',
-  'mediaGenre',
-  'mediaMimeType',
-  'mediaTitle',
-  'mediaTrack',
-  'mediaYearRecorded',
-];
-
-/**
- * Path of a worker script.
- * @public {string}
- */
-ContentMetadataProvider.WORKER_SCRIPT =
-    'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/' +
-    'foreground/js/metadata/metadata_dispatcher.js';
+  }
 
-/**
+  /**
    * Converts content metadata from parsers to the internal format.
    * @param {Object} metadata The content metadata.
    * @return {!MetadataItem} Converted metadata.
    */
-ContentMetadataProvider.convertContentMetadata = metadata => {
+  static convertContentMetadata(metadata) {
     const item = new MetadataItem();
     item.contentImageTransform = metadata['imageTransform'];
     item.contentThumbnailTransform = metadata['thumbnailTransform'];
@@ -90,14 +57,10 @@ ContentMetadataProvider.convertContentMetadata = metadata => {
     item.imageWidth = metadata['width'];
     item.mediaMimeType = metadata['mimeType'];
     return item;
-};
-
-ContentMetadataProvider.prototype.__proto__ = MetadataProvider.prototype;
+  }
 
-/**
- * @override
- */
-ContentMetadataProvider.prototype.get = function(requests) {
+  /** @override */
+  get(requests) {
     if (!requests.length) {
       return Promise.resolve([]);
     }
@@ -110,9 +73,9 @@ ContentMetadataProvider.prototype.get = function(requests) {
                                 }).bind(null, requests[i])));
     }
     return Promise.all(promises);
-};
+  }
 
-/**
+  /**
    * Fetches the metadata.
    * @param {!Entry} entry File entry.
    * @param {!Array<string>} names Requested metadata type.
@@ -120,7 +83,7 @@ ContentMetadataProvider.prototype.get = function(requests) {
    *     This callback is called asynchronously.
    * @private
    */
-ContentMetadataProvider.prototype.getImpl_ = function(entry, names, callback) {
+  getImpl_(entry, names, callback) {
     if (entry.isDirectory) {
       setTimeout(
           callback.bind(
@@ -147,19 +110,19 @@ ContentMetadataProvider.prototype.getImpl_ = function(entry, names, callback) {
       return;
     }
     this.getFromMediaGalleries_(entry, names).then(callback);
-};
+  }
 
-/**
+  /**
    * Gets a metadata from mediaGalleries API
    *
    * @param {!Entry} entry File entry.
    * @param {!Array<string>} names Requested metadata type.
- * @return {!Promise<!MetadataItem>}  Promise that resolves with the metadata of
+   * @return {!Promise<!MetadataItem>}  Promise that resolves with the metadata
+   *     of
    *    the entry.
    * @private
    */
-ContentMetadataProvider.prototype.getFromMediaGalleries_ = function(
-    entry, names) {
+  getFromMediaGalleries_(entry, names) {
     const self = this;
     return new Promise((resolve, reject) => {
       entry.file(
@@ -192,14 +155,14 @@ ContentMetadataProvider.prototype.getFromMediaGalleries_ = function(
                 'failed to open file entry'));
           });
     });
-};
+  }
 
-/**
+  /**
    * Dispatches a message from a metadata reader to the appropriate on* method.
    * @param {Object} event The event.
    * @private
    */
-ContentMetadataProvider.prototype.onMessage_ = function(event) {
+  onMessage_(event) {
     const data = event.data;
     switch (data.verb) {
       case 'initialized':
@@ -224,14 +187,14 @@ ContentMetadataProvider.prototype.onMessage_ = function(event) {
         assertNotReached();
         break;
     }
-};
+  }
 
-/**
+  /**
    * Handles the 'initialized' message from the metadata reader Worker.
    * @param {RegExp} regexp Regexp of supported urls.
    * @private
    */
-ContentMetadataProvider.prototype.onInitialized_ = function(regexp) {
+  onInitialized_(regexp) {
     this.urlFilter_ = regexp;
 
     // Tests can monitor for this state with
@@ -242,32 +205,33 @@ ContentMetadataProvider.prototype.onInitialized_ = function(regexp) {
     // URL requests in-flight.
     util.testSendMessage('worker-initialized');
     this.initialized_ = true;
-};
+  }
 
-/**
+  /**
    * Handles the 'result' message from the worker.
    * @param {string} url File url.
    * @param {!MetadataItem} metadataItem The metadata item.
    * @private
    */
-ContentMetadataProvider.prototype.onResult_ = function(url, metadataItem) {
+  onResult_(url, metadataItem) {
     const callbacks = this.callbacks_[url];
     delete this.callbacks_[url];
     for (let i = 0; i < callbacks.length; i++) {
       callbacks[i](metadataItem);
     }
-};
+  }
 
-/**
+  /**
    * Handles the 'log' message from the worker.
    * @param {Array<*>} arglist Log arguments.
    * @private
    */
-ContentMetadataProvider.prototype.onLog_ = arglist => {
-  console.log.apply(console, ['ContentMetadataProvider log:'].concat(arglist));
-};
+  onLog_(arglist) {
+    console.log.apply(
+        console, ['ContentMetadataProvider log:'].concat(arglist));
+  }
 
-/**
+  /**
    * Dispatches a message from MediaGalleries API to the appropriate on* method.
    * @param {!Entry} entry File entry.
    * @param {!Object} metadata The metadata from MediaGalleries API.
@@ -275,8 +239,7 @@ ContentMetadataProvider.prototype.onLog_ = arglist => {
    *    converted metadata item.
    * @private
    */
-ContentMetadataProvider.prototype.convertMediaMetadataToMetadataItem_ =
-    function(entry, metadata) {
+  convertMediaMetadataToMetadataItem_(entry, metadata) {
     return new Promise((resolve, reject) => {
       if (!metadata) {
         resolve(this.createError_(
@@ -352,9 +315,9 @@ ContentMetadataProvider.prototype.convertMediaMetadataToMetadataItem_ =
         resolve(item);
       }
     });
-};
+  }
 
-/**
+  /**
    * Handles the 'error' message from the worker.
    * @param {string} url File entry.
    * @param {string} step Step failed.
@@ -362,8 +325,7 @@ ContentMetadataProvider.prototype.convertMediaMetadataToMetadataItem_ =
    * @return {!MetadataItem} Error metadata
    * @private
    */
-ContentMetadataProvider.prototype.createError_ =
-    (url, step, errorDescription) => {
+  createError_(url, step, errorDescription) {
     // For error case, fill all fields with error object.
     const error =
         new ContentMetadataProvider.Error(url, step, errorDescription);
@@ -372,32 +334,55 @@ ContentMetadataProvider.prototype.createError_ =
     item.contentThumbnailTransformError = error;
     item.contentThumbnailUrlError = error;
     return item;
-    };
+  }
+}
 
 /**
  * Content metadata provider error.
+ */
+ContentMetadataProvider.Error = class extends Error {
+  /**
    * @param {string} url File Entry.
    * @param {string} step Step failed.
    * @param {string} errorDescription Error description.
- * @constructor
- * @struct
- * @extends {Error}
- */
-ContentMetadataProvider.Error = function(url, step, errorDescription) {
-  /**
-   * @public {string}
    */
+  constructor(url, step, errorDescription) {
+    super(errorDescription);
+
+    /** @public @const {string} */
     this.url = url;
 
-  /**
-   * @public {string}
-   */
+    /** @public @const {string} */
     this.step = step;
 
-  /**
-   * @public {string}
-   */
+    /** @public @const {string} */
     this.errorDescription = errorDescription;
+  }
 };
 
-ContentMetadataProvider.Error.prototype.__proto__ = Error.prototype;
+/** @public @const {!Array<string>} */
+ContentMetadataProvider.PROPERTY_NAMES = [
+  'contentImageTransform',
+  'contentThumbnailTransform',
+  'contentThumbnailUrl',
+  'exifLittleEndian',
+  'ifd',
+  'imageHeight',
+  'imageWidth',
+  'mediaAlbum',
+  'mediaArtist',
+  'mediaDuration',
+  'mediaGenre',
+  'mediaMimeType',
+  'mediaTitle',
+  'mediaTrack',
+  'mediaYearRecorded',
+];
+
+/**
+ * Path of a worker script.
+ * @public @const {string}
+ */
+ContentMetadataProvider.WORKER_SCRIPT =
+    'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj/' +
+    'foreground/js/metadata/metadata_dispatcher.js';