Check origin before providing initData in encrypted event

Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 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 1546 matching lines @@
     }
 
     if (!document().contentSecurityPolicy()->allowMediaFromSource(url)) {
         WTF_LOG(Media, "HTMLMediaElement::isSafeToLoadURL(%p, %s) -> rejected by Content Security Policy", this, urlForLoggingMedia(url).utf8().data());
         return false;
     }
 
     return true;
 }
 
+bool HTMLMediaElement::isMediaDataCORSSameOrigin(SecurityOrigin* origin) const
+{
+    // hasSingleSecurityOrigin() tells us whether the origin in the src is
+    // the same as the actual request (i.e. after redirect).
+    // didPassCORSAccessCheck() means it was a successful CORS-enabled fetch
+    // (vs. non-CORS-enabled or failed).
+    // taintsCanvas() does checkAccess() on the URL plus allow data sources,
+    // to ensure that it is not a URL that requires CORS (basically same
+    // origin).
+    return hasSingleSecurityOrigin() && ((webMediaPlayer() && webMediaPlayer()->didPassCORSAccessCheck()) || !origin->taintsCanvas(currentSrc()));
+}
+
 void HTMLMediaElement::startProgressEventTimer()
 {
     if (m_progressEventTimer.isActive())
         return;
 
     m_previousProgressTime = WTF::currentTime();
     // 350ms is not magic, it is in the spec!
     m_progressEventTimer.startRepeating(0.350, FROM_HERE);
 }
 
@@ skipping 2534 matching lines @@
 
 #if ENABLE(WEB_AUDIO)
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!visitor->isAlive(m_audioSourceNode) && audioSourceProvider())
         audioSourceProvider()->setClient(nullptr);
 }
 #endif
 
 }