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

ui/file_manager/image_loader/request.js

Index: ui/file_manager/image_loader/request.js
diff --git a/ui/file_manager/image_loader/request.js b/ui/file_manager/image_loader/request.js
index e8cd3a5e742470fd98033873bfa7e9332162b674..b8b6c6f8ab3f8acf9c7592ec8374c91964d30d54 100644
--- a/ui/file_manager/image_loader/request.js
+++ b/ui/file_manager/image_loader/request.js
@@ -236,8 +236,14 @@ Request.prototype.downloadOriginal_ = function(onSuccess, onFailure) {
   }
 
   // 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;