EME: Implement Session Closed algorithm

third_party/WebKit/Source/modules/encryptedmedia/MediaKeySession.cpp

 /*
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 822 matching lines @@
   }
   init.setMessage(
       DOMArrayBuffer::create(static_cast<const void*>(message), messageLength));
 
   MediaKeyMessageEvent* event =
       MediaKeyMessageEvent::create(EventTypeNames::message, init);
   event->setTarget(this);
   m_asyncEventQueue->enqueueEvent(event);
 }
 
 void MediaKeySession::close() {

[ddorwin, 2016/10/11 01:41:07]

This method is overloaded with the implementation of the close() in the spec. It
should really be closed() or something.

That leaves message() as an outlier. See also the naming comment below. onFoo
style would make this much clearer, but I guess that's not used here.

[jrummell, 2016/10/11 18:47:35]

Since we're switching blink to Chromium style, we could switch to onXxx. Opened
http://crbug.com/654834.

   DVLOG(MEDIA_KEY_SESSION_LOG_LEVEL) << __func__ << "(" << this << ")";
 
-  // From https://w3c.github.io/encrypted-media/#session-close:
-  // The following steps are run:
-  // 1. Let the session be the associated MediaKeySession object.
-  // 2. Let promise be the closed attribute of the session.
-  // 3. Resolve promise.
+  // From http://w3c.github.io/encrypted-media/#session-closed
+  // 1. Let session be the associated MediaKeySession object.
+  // 2. If session's session type is "persistent-usage-record", execute the
+  //    following steps in parallel:
+  //    1. Let cdm be the CDM instance represented by session's cdm instance
+  //       value.
+  //    2. Use cdm to store session's record of key usage, if it exists.
+  //    ("persistent-usage-record" not supported by Chrome.)
+
+  // 3. Run the Update Key Statuses algorithm on the session, providing an
+  //    empty sequence.
+  keysStatusesChange(WebVector<WebEncryptedMediaKeyInformation>(), false);
+
+  // 4. Run the Update Expiration algorithm on the session, providing NaN.
+  expirationChanged(std::numeric_limits<double>::quiet_NaN());

[ddorwin, 2016/10/11 01:41:07]

Unrelated to this CL, it's odd that we have ChangeD here and Change above.

[jrummell, 2016/10/11 18:47:35]

Agreed.

+
+  // 5. Let promise be the closed attribute of the session.
+  // 6. Resolve promise.
   m_closedPromise->resolve(ToV8UndefinedGenerator());
 
-  // Once closed, the session can no longer be the target of events from
-  // the CDM so this object can be garbage collected.
+  // After this algorithm has run, event handlers for the events queued by
+  // this algorithm will be executed, but no further events can be queued.
+  // As a result, no messages can be sent by the CDM as a result of closing
+  // the session.
   m_isClosed = true;
 }
 
 void MediaKeySession::expirationChanged(double updatedExpiryTimeInMS) {
   DVLOG(MEDIA_KEY_SESSION_LOG_LEVEL) << __func__ << "(" << this << ") "
                                      << updatedExpiryTimeInMS;
 
   // From https://w3c.github.io/encrypted-media/#update-expiration:
   // The following steps are run:
   // 1. Let the session be the associated MediaKeySession object.
@@ skipping 92 matching lines @@
   visitor->trace(m_asyncEventQueue);
   visitor->trace(m_pendingActions);
   visitor->trace(m_mediaKeys);
   visitor->trace(m_keyStatusesMap);
   visitor->trace(m_closedPromise);
   EventTargetWithInlineData::trace(visitor);
   ActiveDOMObject::trace(visitor);
 }
 
 }  // namespace blink