Bug 1398659. P3 - ChannelMediaResource::Open() is a no-op for a cloned resource. r=gerald

1. mChannel is null.
2. mCacheStream has been initialized by InitAsClone().

So ChannelMediaDecoder::Load() doesn't need to call OpenResource(nullptr) at all.

MozReview-Commit-ID: FeARp9fu65L

--HG--
extra : rebase_source : ee3ae9bfa6830ed18fea152e12da18e181870d2d
extra : intermediate-source : 6b78ae143afa325b378d7cc2cbd2e3e0bcfdfe93
extra : source : 098787b9606b70697a3b1762b35a488799995475

dom/media/ChannelMediaDecoder.cpp

@@ -283,9 +283,6 @@ ChannelMediaDecoder::Load(BaseMediaResource* aOriginal)
     return rv;
   }
 
-  rv = OpenResource(nullptr);
-  NS_ENSURE_SUCCESS(rv, rv);
-
   SetStateMachine(CreateStateMachine());
   NS_ENSURE_TRUE(GetStateMachine(), NS_ERROR_FAILURE);