[Files app] ES6 class for metadata_parser_logger.js

Bug: 778674
Change-Id: I7e9586b21be4db311fadd06b2fbd457daf9711b3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647498
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@{#666602}

ui/file_manager/externs/metadata_worker_window.js

@@ -5,36 +5,38 @@
 /**
  * @interface
  */
-function MetadataParserLogger() {}
+class MetadataParserLogger {
+  constructor() {
+    /**
+     * Verbose logging for the dispatcher.
+     * Individual parsers also take this as their default verbosity setting.
+     * @public {boolean}
+     */
+    this.verbose;
+  }
 
-/**
- * Verbose logging for the dispatcher.
- *
- * Individual parsers also take this as their default verbosity setting.
- */
-MetadataParserLogger.prototype.verbose;
+  /**
+   * Indicate to the caller that an operation has failed.
+   *
+   * No other messages relating to the failed operation should be sent.
+   * @param {...(Object|string)} var_args Arguments.
+   */
+  error(var_args) {}
 
-/**
- * Indicate to the caller that an operation has failed.
- *
- * No other messages relating to the failed operation should be sent.
- * @param {...(Object|string)} var_args Arguments.
- */
-MetadataParserLogger.prototype.error = function(var_args) {};
+  /**
+   * Send a log message to the caller.
+   *
+   * Callers must not parse log messages for control flow.
+   * @param {...(Object|string)} var_args Arguments.
+   */
+  log(var_args) {}
 
-/**
- * Send a log message to the caller.
- *
- * Callers must not parse log messages for control flow.
- * @param {...(Object|string)} var_args Arguments.
- */
-MetadataParserLogger.prototype.log = function(var_args) {};
-
-/**
- * Send a log message to the caller only if this.verbose is true.
- * @param {...(Object|string)} var_args Arguments.
- */
-MetadataParserLogger.prototype.vlog = function(var_args) {};
+  /**
+   * Send a log message to the caller only if this.verbose is true.
+   * @param {...(Object|string)} var_args Arguments.
+   */
+  vlog(var_args) {}
+}
 
 /**
  * @param {function(new:MetadataParser, !MetadataParserLogger)} parserClass
@@ -47,5 +49,5 @@ var registerParserClass = function(parserClass) {};
  * @param {function(!Entry)} successCallback
  * @param {function(!FileError)=} opt_errorCallback
  */
-var webkitResolveLocalFileSystemURL =
-    function(url, successCallback, opt_errorCallback) {};
+var webkitResolveLocalFileSystemURL = function(
+    url, successCallback, opt_errorCallback) {};