Start to use new metadata item in ImageEncoder.

ui/file_manager/gallery/js/image_editor/image_encoder_unittest.js

 // Copyright 2014 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.
 'use strict';
 
 /**
  * Encodes an image to data URL by using ImageEncoder.getBlob.
  */
 function encodeAnImageAsDataURL(canvas, metadata, imageQuality) {
   return new Promise(function(resolve, reject) {
@@ skipping 13 matching lines @@
 }
 
 /**
  * Test case for png image.
  * Png image should be saved as a png image.
  */
 function testPngImage(callback) {
   var canvas = getSampleCanvas();
 
   var metadata = {
-    media: {
-      mimeType: 'image/png',
-    }
+    mediaMimeType: 'image/png'
   };
 
   reportPromise(encodeAnImageAsDataURL(canvas, metadata, 0.9).then(
       function(result) {
         assertEquals(canvas.toDataURL('image/png'), result);
       }), callback);
 }
 
 /**
  * Test case for jpeg image.
  * Jpeg image should be saved as a jpeg image. Since we don't include
  * exif_encoder.js in this test, no metadata is added to the blob.
  */
 function testJpegImage(callback) {
   var canvas = getSampleCanvas();
 
   var metadata = {
-    media: {
-      mimeType: 'image/jpeg',
-    }
+    mediaMimeType: 'image/jpeg'
   };
 
   reportPromise(encodeAnImageAsDataURL(canvas, metadata, 0.9).then(
       function(result) {
         assertEquals(canvas.toDataURL('image/jpeg', 0.9), result);
       }), callback);
 }
 
 
 /**
  * Test case of webp image.
  * Image should be saved as a image/png since chrome doesn't support to
  * encode other than image/jpeg or image/png.
  */
 function testWebpImage(callback) {
   var canvas = getSampleCanvas();
 
   var metadata = {
-    media: {
-      mimeType: 'image/webp'
-    }
+    mediaMimeType: 'image/webp'
   };
 
   reportPromise(encodeAnImageAsDataURL(canvas, metadata, 0.9).then(
       function(result) {
         assertEquals(canvas.toDataURL('image/png'), result);
       }), callback);
 }
 
 /**
  * Test case for broken metadata.
  */
 function testWithBrokenMetadata() {
   var canvas = getSampleCanvas();
 
   var metadata = {
-    media: {
-      // No mimetype field.
-    }
+    // No mimetype field.
   };
 
   // An exception should be thrown if metadata is broken.
   assertThrows(function() {
     var encoder = ImageEncoder.encodeMetadata(metadata, canvas);
   });
 }