--- a/dom/webidl/MediaKeySystemAccess.webidl
+++ b/dom/webidl/MediaKeySystemAccess.webidl
@@ -5,28 +5,35 @@
  *
  * The origin of this IDL file is
  * https://dvcs.w3.org/hg/html-media/raw-file/default/encrypted-media/encrypted-media.html
  *
  * Copyright © 2014 W3C® (MIT, ERCIM, Keio, Beihang), All Rights Reserved.
  * W3C liability, trademark and document use rules apply.
  */
 
+enum MediaKeysRequirement {
+  "required",
+  "optional",
+  "not-allowed"
+};
+
 dictionary MediaKeySystemMediaCapability {
    DOMString contentType = "";
-   // TODO: robustness
+   DOMString robustness = "";
 };
 
 dictionary MediaKeySystemConfiguration {
   DOMString                               label = "";
-  sequence<DOMString>                     initDataTypes;
-  sequence<MediaKeySystemMediaCapability> audioCapabilities;
-  sequence<MediaKeySystemMediaCapability> videoCapabilities;
-
-   // TODO: distinctiveIdentifier, persistentState, sessionTypes  
+  sequence<DOMString>                     initDataTypes = [];
+  sequence<MediaKeySystemMediaCapability> audioCapabilities = [];
+  sequence<MediaKeySystemMediaCapability> videoCapabilities = [];
+  MediaKeysRequirement                    distinctiveIdentifier = "optional";
+  MediaKeysRequirement                    persistentState = "optional";
+  sequence<DOMString>                     sessionTypes;
 };
 
 [Pref="media.eme.apiVisible"]
 interface MediaKeySystemAccess {
   readonly    attribute DOMString keySystem;
   [NewObject]
   MediaKeySystemConfiguration getConfiguration();
   [NewObject]

--- a/dom/webidl/MediaKeys.webidl
+++ b/dom/webidl/MediaKeys.webidl
@@ -5,20 +5,26 @@
  *
  * The origin of this IDL file is
  * https://dvcs.w3.org/hg/html-media/raw-file/default/encrypted-media/encrypted-media.html
  *
  * Copyright © 2014 W3C® (MIT, ERCIM, Keio, Beihang), All Rights Reserved.
  * W3C liability, trademark and document use rules apply.
  */
 
-enum SessionType { "temporary", "persistent" };
+// Note: "persistent-usage-record" session type is unsupported yet, as
+// it's marked as "at risk" in the spec, and Chrome doesn't support it. 
+enum MediaKeySessionType {
+  "temporary",
+  "persistent-license",
+  // persistent-usage-record,
+};
 
 [Pref="media.eme.apiVisible"]
 interface MediaKeys {
   readonly attribute DOMString keySystem;
 
   [NewObject, Throws]
-  MediaKeySession createSession(optional SessionType sessionType = "temporary");
+  MediaKeySession createSession(optional MediaKeySessionType sessionType = "temporary");
 
   [NewObject]
   Promise<void> setServerCertificate((ArrayBufferView or ArrayBuffer) serverCertificate);
 };