The Registrar class is unnecessary, as SkFlattenable factory
registration is now handled via initialization routines that can just
call the Register function directly.
Also, no need to lazily initialize gCount to 0, as initializing an int
to a constant value does not require dynamic initialization. (C++
actually guarantees zero initialization of global ints anyway, but
existing practice in Skia appears to favor the explicit "= 0").
Relatedly, this requires removing the unused/unimplemented
SkLayerDrawLooper::MyRegistrar class. And removing that allows Clang
to realize that SkLayerDrawLooper::fTopRec is unneeded too, so remove
that too to squelch the compiler warning/error.
This doesn't change any public API.
TBR=reed@google.com
Review URL: https://codereview.chromium.org/1361323002
00d6e515e5