Files.app: Add metrics of RAW file loading time.

ui/file_manager/image_loader/request.js

 // Copyright 2013 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.
 
 /**
  * @typedef {{
  *   cache: (boolean|undefined),
  *   priority: (number|undefined),
  *   taskId: number,
  *   timestamp: (number|undefined),
@@ skipping 218 matching lines @@
 
   // Download data urls directly since they are not supported by XmlHttpRequest.
   var dataUrlMatches = this.request_.url.match(/^data:([^,;]*)[,;]/);
   if (dataUrlMatches) {
     this.image_.src = this.request_.url;
     this.contentType_ = dataUrlMatches[1];
     return;
   }
 
   // Load RAW images by using Piex loader instead of XHR.
-  if (FileType.getTypeForName(this.request_.url).type === 'raw') {
+  var fileType = FileType.getTypeForName(this.request_.url);
+  if (fileType.type === 'raw') {
+    var timer = metrics.getTracker().startTiming(
+        metrics.Categories.INTERNALS,
+        metrics.timing.Variables.EXTRACT_JPEG_FROM_RAW,
+        fileType.subtype);
     this.piexLoader_.load(this.request_.url).then(function(data) {
+      timer.send();
       var blob = new Blob([data.thumbnail], {type: 'image/jpeg'});
       var url = URL.createObjectURL(blob);
       this.image_.src = url;
       this.request_.orientation = data.orientation;
       this.request_.colorSpace = data.colorSpace;
     }.bind(this), function(error) {
       console.error('PiexLoaderError: ', error);
       onFailure();
     });
     return;
@@ skipping 276 matching lines @@
   this.image_.src = 'data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAA' +
       'ABAAEAAAICTAEAOw==';
 
   this.xhr_.onload = function() {};
   this.xhr_.abort();
 
   // Dispose memory allocated by Canvas.
   this.canvas_.width = 0;
   this.canvas_.height = 0;
 };