This would let us get rid of a bunch of if (mObserver) checks in the decoders. The only place where we have a null observer at the moment is imgTools, but that code could just instantiate an nsStubImageDecoderObserver and pass it in.

Is this something we're still interested in doing?

(In reply to Ali Juma [:ajuma] from comment #1) > Is this something we're still interested in doing? Yes, unless joe disagrees here.

I'm pretty sure we have other examples of this too, but I totally agree that we should just make it impossible.