Set callback interface on WebCDMSession after creation.

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 53 matching lines @@
 {
     MediaKeySession* session = adoptRefCountedGarbageCollectedWillBeNoop(new MediaKeySession(context, cdm, keys));
     session->suspendIfNeeded();
     return session;
 }
 
 MediaKeySession::MediaKeySession(ExecutionContext* context, blink::WebContentDecryptionModule* cdm, MediaKeys* keys)
     : ActiveDOMObject(context)
     , m_keySystem(keys->keySystem())
     , m_asyncEventQueue(GenericEventQueue::create(this))
-    , m_session(adoptPtr(cdm->createSession(this)))
+    , m_session(adoptPtr(cdm->createSession()))
     , m_keys(keys)
     , m_isClosed(false)
     , m_actionTimer(this, &MediaKeySession::actionTimerFired)
 {
     WTF_LOG(Media, "MediaKeySession::MediaKeySession");
     ScriptWrappable::init(this);
-    ASSERT(m_session);
+    m_session->setClientInterface(this);

[ddorwin, 2014/07/10 23:22:30]

The point of this change is to allow refactoring. Is there a reason not to do
that refactoring in this CL, which will land after the Chromium side anyway, so
that we can make sure the interface and Chromium changes enable that
refactoring?

[jrummell, 2014/07/11 00:55:53]

Without promises implemented, all responses come back as events. Need to
register the interface so we get something back.

 }
 
 MediaKeySession::~MediaKeySession()
 {
     m_session.clear();
 #if !ENABLE(OILPAN)
     // MediaKeySession and m_asyncEventQueue always become unreachable
     // together. So MediaKeySession and m_asyncEventQueue are destructed in the
     // same GC. We don't need to call cancelAllEvents explicitly in Oilpan.
     m_asyncEventQueue->cancelAllEvents();
@@ skipping 206 matching lines @@
 
 void MediaKeySession::trace(Visitor* visitor)
 {
     visitor->trace(m_error);
     visitor->trace(m_asyncEventQueue);
     visitor->trace(m_keys);
     EventTargetWithInlineData::trace(visitor);
 }
 
 }