Bug: 15683945
invokeFunctor() does not require isEnabled() to be true
to execute. Specifically it does not care if HardwareRenderer
has a Surface or not, as it will fall back to a pbuffer surface
if available. If there is no context at all, it will invoke
with kModeProcessNoContext.
Change-Id: Ie6abe566b92c8fa33bb7a673fc3b9fa9ce913446