Check origin before providing initData in encrypted event

Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp

Index: Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp
diff --git a/Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp b/Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp
index 491969d5945e038c1bf6f200b75de05e885efb29..4bf8eab1268fdbbe30feddd961c7c9f090cfb7f1 100644
--- a/Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp
+++ b/Source/modules/encryptedmedia/HTMLMediaElementEncryptedMedia.cpp
@@ -515,8 +515,15 @@ void HTMLMediaElementEncryptedMedia::encrypted(HTMLMediaElement& element, const
 
     if (RuntimeEnabledFeatures::encryptedMediaEnabled()) {
         // Send event for WD EME.
-        // FIXME: Check origin before providing initData. http://crbug.com/418233.
-        RefPtrWillBeRawPtr<Event> event = createEncryptedEvent(initDataType, initData, initDataLength);
+        RefPtrWillBeRawPtr<Event> event;
+        if (element.isMediaDataCORSSameOrigin(element.executionContext()->securityOrigin())) {
+            event = createEncryptedEvent(initDataType, initData, initDataLength);
+        } else {
+            // Current page is not allowed to see content from the media file,
+            // so don't return the initData. However, they still get an event.
+            event = createEncryptedEvent(emptyString(), nullptr, 0);
+        }
+
         event->setTarget(&element);
         element.scheduleEvent(event.release());
     }