Make MediaSession per frame as an attribute of Navigator

third_party/WebKit/LayoutTests/media/mediasession/resources/utils.js

+function assert_image_equals(expected, observed) {
+  assert_equals(expected.src, observed.src);
+  assert_equals(expected.type, observed.type);
+  assert_equals(expected.sizes, observed.sizes);
+}
+
+function assert_metadata_equals(expected, observed) {
+  assert_equals(expected.title, observed.title);
+  assert_equals(expected.artist, observed.artist);
+  assert_equals(expected.album, observed.album);
+  assert_equals(expected.artwork.length, observed.artwork.length);
+  for (var i = 0; i < expected.artwork.length; i++) {

[mlamouri (slow - plz ping), 2016/10/10 20:30:34]

style: you can drop { }

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+    assert_image_equals(expected.artwork[i], observed.artwork[i]);
+  }
+}
+
+function mojoString16ToJS(mojoString16) {
+  return String.fromCharCode.apply(this, mojoString16.data);

[whywhat, 2016/10/10 20:45:09]

nit: seems like everywhere else null is passed as the first argument

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+}
+
+function mojoImageToJS(mojoImage) {
+  var src = mojoImage.src.url;
+  var type = mojoString16ToJS(mojoImage.type);
+  var sizes = "";
+  for (var i = 0; i < mojoImage.sizes.length; i++) {
+    if (i > 0) {

[mlamouri (slow - plz ping), 2016/10/10 20:30:34]

style: ditto

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+      sizes = sizes + " ";

[whywhat, 2016/10/10 20:45:09]

nit: +=

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+    }
+    var mojoSize = mojoImage.sizes[i];
+    sizes = sizes + mojoSize.width.toString() + "x" + mojoSize.height.toString();

[whywhat, 2016/10/10 20:45:09]

nit: ditto

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+  }
+  return { src: src, type: type, sizes: sizes };
+}
+
+function mojoMetadataToJS(mojoMetadata) {
+  var title = mojoString16ToJS(mojoMetadata.title);
+  var artist = mojoString16ToJS(mojoMetadata.artist);
+  var album = mojoString16ToJS(mojoMetadata.album);
+  var artwork = [];
+  for (var i = 0; i < mojoMetadata.artwork.length; i++) {

[mlamouri (slow - plz ping), 2016/10/10 20:30:34]

style: ditto

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+    artwork.push(mojoImageToJS(mojoMetadata.artwork[i]));
+  }
+  return new MediaMetadata({title: title, artist: artist, album: album, artwork: artwork});
+}