Protocol handler interface for the resource:// protocol
Sets the substitution for the root key:
resource://root/path ==> baseURI.resolve(path)
A null baseURI removes the specified substitution.
A root key should always be lowercase; however, this may not be
enforced.
Gets the substitution for the root key.
@throws NS_ERROR_NOT_AVAILABLE if none exists.
Returns TRUE if the substitution exists and FALSE otherwise.
Utility function to resolve a resource URI. A resolved URI is not
guaranteed to reference a resource that exists (ie. opening a channel to
the resolved URI may fail).
@throws NS_ERROR_NOT_AVAILABLE if resURI.host() is an unknown root key.