[Files app] ES6 class for external_metadata_provider.js

Bug: 778674
Change-Id: I14c981ffc87b504e5dd1dfca57097e627a72a06b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647641
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@{#666611}

ui/file_manager/file_manager/foreground/js/metadata/external_metadata_provider.js

@@ -5,55 +5,15 @@
 /**
  * Metadata provider for FileEntry#getMetadata.
  * TODO(hirono): Rename thumbnailUrl with externalThumbnailUrl.
- *
- * @constructor
- * @extends {MetadataProvider}
- * @struct
+ * @final
  */
-function ExternalMetadataProvider() {
-  MetadataProvider.call(this, ExternalMetadataProvider.PROPERTY_NAMES);
-}
-
-/**
- * @const {!Array<string>}
- */
-ExternalMetadataProvider.PROPERTY_NAMES = [
-  'alternateUrl',
-  'availableOffline',
-  'availableWhenMetered',
-  'contentMimeType',
-  'croppedThumbnailUrl',
-  'customIconUrl',
-  'dirty',
-  'externalFileUrl',
-  'hosted',
-  'imageHeight',
-  'imageRotation',
-  'imageWidth',
-  'modificationTime',
-  'modificationByMeTime',
-  'pinned',
-  'present',
-  'shared',
-  'sharedWithMe',
-  'size',
-  'thumbnailUrl',
-  'canCopy',
-  'canDelete',
-  'canRename',
-  'canAddChildren',
-  'canShare',
-  'isMachineRoot',
-  'isExternalMedia',
-  'isArbitrarySyncFolder',
-];
-
-ExternalMetadataProvider.prototype.__proto__ = MetadataProvider.prototype;
+class ExternalMetadataProvider extends MetadataProvider {
+  constructor() {
+    super(ExternalMetadataProvider.PROPERTY_NAMES);
+  }
 
-/**
- * @override
- */
-ExternalMetadataProvider.prototype.get = function(requests) {
+  /** @override */
+  get(requests) {
     if (!requests.length) {
       return Promise.resolve([]);
     }
@@ -78,17 +38,16 @@ ExternalMetadataProvider.prototype.get = function(requests) {
             }
           });
     });
-};
+  }
 
-/**
+  /**
    * @param {!Array<!MetadataRequest>} requests
    * @param {!Object<boolean>} nameMap A map of property names that will be used
    *     to copy the value from |propertiesList|.
    * @param {!Array<!chrome.fileManagerPrivate.EntryProperties>} propertiesList
    * @return {!Array<!MetadataItem>}
    */
-ExternalMetadataProvider.prototype.convertResults_ =
-    (requests, nameMap, propertiesList) => {
+  convertResults_(requests, nameMap, propertiesList) {
     const results = [];
     for (let i = 0; i < propertiesList.length; i++) {
       const prop = propertiesList[i];
@@ -96,8 +55,7 @@ ExternalMetadataProvider.prototype.convertResults_ =
       if (prop.alternateUrl !== undefined || nameMap['alternateUrl']) {
         item.alternateUrl = prop.alternateUrl;
       }
-        if (prop.availableOffline !== undefined ||
-            nameMap['availableOffline']) {
+      if (prop.availableOffline !== undefined || nameMap['availableOffline']) {
         item.availableOffline = prop.availableOffline;
       }
       if (prop.availableWhenMetered !== undefined ||
@@ -132,8 +90,7 @@ ExternalMetadataProvider.prototype.convertResults_ =
       if (prop.imageWidth !== undefined || nameMap['imageWidth']) {
         item.imageWidth = prop.imageWidth;
       }
-        if (prop.modificationTime !== undefined ||
-            nameMap['modificationTime']) {
+      if (prop.modificationTime !== undefined || nameMap['modificationTime']) {
         item.modificationTime = new Date(prop.modificationTime);
       }
       if (prop.modificationByMeTime !== undefined ||
@@ -186,4 +143,37 @@ ExternalMetadataProvider.prototype.convertResults_ =
       results.push(item);
     }
     return results;
-    };
+  }
+}
+
+/** @const {!Array<string>} */
+ExternalMetadataProvider.PROPERTY_NAMES = [
+  'alternateUrl',
+  'availableOffline',
+  'availableWhenMetered',
+  'contentMimeType',
+  'croppedThumbnailUrl',
+  'customIconUrl',
+  'dirty',
+  'externalFileUrl',
+  'hosted',
+  'imageHeight',
+  'imageRotation',
+  'imageWidth',
+  'modificationTime',
+  'modificationByMeTime',
+  'pinned',
+  'present',
+  'shared',
+  'sharedWithMe',
+  'size',
+  'thumbnailUrl',
+  'canCopy',
+  'canDelete',
+  'canRename',
+  'canAddChildren',
+  'canShare',
+  'isMachineRoot',
+  'isExternalMedia',
+  'isArbitrarySyncFolder',
+];