Media Session API: make MediaMetadata mutable.

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

Index: third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/utils.js
diff --git a/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/utils.js b/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/utils.js
index e1cfa6f5eedd4f44772f18bb3b6108a6caab2de6..f8947a60f9210675a50adad902622f06d1e28d73 100644
--- a/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/utils.js
+++ b/third_party/WebKit/LayoutTests/media/mediasession/mojo/resources/utils.js
@@ -5,11 +5,11 @@ function assert_image_equals(expected, observed) {
 }
 
 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++) {
+  assert_equals(expected.title, observed.title, 'metadata.title');
+  assert_equals(expected.artist, observed.artist, 'metadata.artist');
+  assert_equals(expected.album, observed.album, 'metadata.album');
+  assert_equals(expected.artwork.length, observed.artwork.length,
+                'metadata.artwork.length');
+  for (var i = 0; i < expected.artwork.length; i++)
     assert_image_equals(expected.artwork[i], observed.artwork[i]);
-  }
 }