Bug 1265587 - Force keystatuses to be cleared when Widevine keysessions are closed. r=gerald

The Widevine CDM, and I believe the Adobe CDM too probably, do not mark a
session's keys as unusable when a key session is closed. This means that
the CDMCaps' copy of the keys that are usable is wrong, and so if the media
with the same keys is reloaded with the same MediaKeys, Firefox will assume
that the keys are usable before the license for the keys has been
re-negotiated, and so decryption will fail.


MozReview-Commit-ID: 1kTDzwSD8PE

dom/html/HTMLMediaElement.cpp

@@ -5147,6 +5147,9 @@ already_AddRefed<Promise>
 HTMLMediaElement::SetMediaKeys(mozilla::dom::MediaKeys* aMediaKeys,
                                ErrorResult& aRv)
 {
+  LOG(LogLevel::Debug, ("%p SetMediaKeys(%p) mMediaKeys=%p mDecoder=%p",
+    this, aMediaKeys, mMediaKeys.get(), mDecoder.get()));
+
   if (MozAudioCaptured()) {
     aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
     return nullptr;