clean up some odd SkRefCnt features

SkRefCntBase is an implementation detail of SkRefCnt, so let's not
mention it in SkContext_Compute.h.  While I'm here, I notice SkNVRefCnt
would work fine too.

No one else calls internal_dispose_restore_refcnt_to_1(), so we can
inline it.  While here, I notice it's resetting the ref count to 1 even
in release builds.  I'm not sure if that is/can be optimized away, but
in any case I think we can wrap with #ifdef SK_DEBUG, if only to make it
clear that it's only there to support the assert in the destructor.

I've removed validate().  Most of the places it's called read pretty
weird, and I think suggest some sort of class-specific validation than
just checking that we're holding a ref.  SkWeakRefCnt::validate() isn't
called anywhere.

There were few users of getRefCnt() outside SkRefCnt itself, so I
removed the rest and made it private.

I've added a few this-> to self calls while at it.

Change-Id: I98be06677a6e8b8e66f44cbb17d14e38b0f39d38
Reviewed-on: https://skia-review.googlesource.com/c/167160
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
7 files changed