Implement MediaMetadata artwork in Blink

third_party/WebKit/Source/modules/mediasession/MediaArtwork.idl

Index: third_party/WebKit/Source/modules/mediasession/MediaArtwork.idl
diff --git a/third_party/WebKit/Source/modules/mediasession/MediaArtwork.idl b/third_party/WebKit/Source/modules/mediasession/MediaArtwork.idl
new file mode 100644
index 0000000000000000000000000000000000000000..498e0554ffe2a88db23c1696e3cb596ecd3e652f
--- /dev/null
+++ b/third_party/WebKit/Source/modules/mediasession/MediaArtwork.idl
@@ -0,0 +1,13 @@
+// Copyright 2016 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.
+
+[
+    ConstructorCallWith=ExecutionContext,
+    Constructor(MediaArtworkInit artwork),
+    RuntimeEnabled=MediaSession,
+] interface MediaArtwork {
+  readonly attribute DOMString src;
+  readonly attribute DOMString sizes;
+  readonly attribute DOMString type;
+};