Verify MediaKeys parameter values consistently

Source/modules/encryptedmedia/MediaKeys.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 35 matching lines @@
     // From <http://dvcs.w3.org/hg/html-media/raw-file/default/encrypted-media/encrypted-media.html#dom-media-keys-constructor>:
     // The MediaKeys(keySystem) constructor must run the following steps:
 
     // 1. If keySystem is null or an empty string, throw an InvalidAccessError exception and abort these steps.
     if (keySystem.isEmpty()) {
         exceptionState.throwDOMException(InvalidAccessError, "The key system provided is invalid.");
         return nullptr;
     }
 
     // 2. If keySystem is not one of the user agent's supported Key Systems, throw a NotSupportedError and abort these steps.
-    if (!ContentDecryptionModule::supportsKeySystem(keySystem)) {
+    if (!isTypeSupported(keySystem, "")) {

[ddorwin, 2014/02/27 22:44:13]

I don't think we should use the public function for either of these things.
Among other things, we get a log message as if the application made the call.
There might also be logic that we don't need/doesn't make sense.

What we should probably do is encapsulate line 144 in a function -
isSupportedKeySystem() - and call that here and there. That function can
ASSERT(!keySystem.empty()) since callers should have checked that. This is a
super simple wrapper that we would normally avoid, but it helps with the
algorithms, avoiding calling the parent function and encapsulating what internal
function we call to actually check.

[jrummell, 2014/02/27 23:20:00]

Done.

         exceptionState.throwDOMException(NotSupportedError, "The '" + keySystem + "' key system is not supported.");
         return nullptr;
     }
 
     // 3. Let cdm be the content decryption module corresponding to keySystem.
     // 4. Load cdm if necessary.
     OwnPtr<ContentDecryptionModule> cdm = ContentDecryptionModule::create(keySystem);
     if (!cdm) {
         exceptionState.throwDOMException(NotSupportedError, "A content decryption module could not be loaded for the '" + keySystem + "' key system.");
         return nullptr;
@@ skipping 34 matching lines @@
         return nullptr;
     }
 
     if (!initData || !initData->length()) {
         exceptionState.throwDOMException(InvalidAccessError, "The initData provided is null or empty.");
         return nullptr;
     }
 
     // 1. If type contains a MIME type that is not supported or is not supported by the keySystem,
     // throw a NOT_SUPPORTED_ERR exception and abort these steps.
-    if (!m_cdm->supportsMIMEType(contentType)) {
+    if (!isTypeSupported(m_keySystem, contentType)) {

[ddorwin, 2014/02/27 22:44:13]

~Ditto, except maybe step 4 of IST gets encapsulated.

[jrummell, 2014/02/27 23:20:00]

Done.

         exceptionState.throwDOMException(NotSupportedError, "The type provided ('" + contentType + "') is unsupported.");
         return nullptr;
     }
 
     // 2. Create a new MediaKeySession object.
     RefPtrWillBeRawPtr<MediaKeySession> session = MediaKeySession::create(context, m_cdm.get(), m_weakFactory.createWeakPtr());
     // 2.1 Let the keySystem attribute be keySystem.
     ASSERT(!session->keySystem().isEmpty());
     // FIXME: 2.2 Let the state of the session be CREATED.
 
@@ skipping 70 matching lines @@
 
 void MediaKeys::contextDestroyed()
 {
     ContextLifecycleObserver::contextDestroyed();
 
     // We don't need the CDM anymore.
     m_cdm.clear();
 }
 
 }