Add UMA metrics to Photo Editor

chrome/browser/resources/file_manager/js/image_editor/image_encoder.js

 // Copyright (c) 2011 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.
 
 /**
  * A namespace class for image encoding functions. All methods are static.
  */
 function ImageEncoder() {}
 
 ImageEncoder.MAX_THUMBNAIL_DIMENSION = 320;
@@ skipping 53 matching lines @@
  * @param {BlobBuilder} blobBuilder
  * @param {HTMLCanvasElement} canvas The canvas with the image to be encoded.
  * @param {ImageEncoder.MetadataEncoder} metadataEncoder
  * @param {Number} quality (0..1], Encoding quality, default is 0.5
  */
 ImageEncoder.buildBlob = function(
     blobBuilder, canvas, metadataEncoder, quality) {
 
   quality = quality || 0.5;
 
+  ImageUtil.trace.resetTimer('dataurl');
   // WebKit does not support canvas.toBlob yet so canvas.toDataURL is
   // the only way to use the Chrome built-in image encoder.
   var dataURL =
       canvas.toDataURL(metadataEncoder.getMetadata().mimeType, quality);
+  ImageUtil.trace.reportTimer('dataurl');
 
   var encodedImage = ImageEncoder.decodeDataURL(dataURL);
 
   var encodedMetadata = metadataEncoder.encode();
 
   ImageUtil.trace.resetTimer('blob');
   if (encodedMetadata.byteLength != 0) {
     var metadataRange = metadataEncoder.findInsertionRange(encodedImage);
     blobBuilder.append(ImageEncoder.stringToArrayBuffer(
         encodedImage, 0, metadataRange.from));
@@ skipping 108 matching lines @@
     findInsertionRange = function(encodedImage) { return {from: 0, to: 0} };
 
 /**
  * Return serialized metadata ready to write to an image file.
  * The return type is optimized for passing to Blob.append.
  * @return {ArrayBuffer}
  */
 ImageEncoder.MetadataEncoder.prototype.encode = function() {
   return new Uint8Array(0).buffer;
 };