Revert "Revert "SaveLayerRec::fClipMask -> raw pointer""

Revert "Revert "SaveLayerRec::fClipMask -> raw pointer""

This reverts commit 3354969a4a4adcea159f3a0b01ad0a7c04fc9115.

Reason for revert: not the problem?

Original change's description:
> Revert "SaveLayerRec::fClipMask -> raw pointer"
>
> This reverts commit a6b72cb5729306fdd676d739c1e2c53afa0786a7.
>
> Reason for revert: red bots
>
> Original change's description:
> > SaveLayerRec::fClipMask -> raw pointer
> >
> > Use raw pointers for optional clip mask plumbing, to match the backdrop
> > API.
> >
> > Change-Id: I7eb0ee5896faf34cc05789ba0703f35a4ab6a4f2
> > Reviewed-on: https://skia-review.googlesource.com/14901
> > Reviewed-by: Mike Reed <reed@google.com>
> > Commit-Queue: Florin Malita <fmalita@chromium.org>
> >
>
> TBR=fmalita@chromium.org,reed@google.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
>
> Change-Id: I4387620cdc3410018af9cef221e5cf8d09015380
> Reviewed-on: https://skia-review.googlesource.com/14955
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Commit-Queue: Mike Klein <mtklein@chromium.org>
>

TBR=mtklein@chromium.org,reviews@skia.org,fmalita@chromium.org,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I6dde9e0441928f7a7423139a5c39f520f892f4b5
Reviewed-on: https://skia-review.googlesource.com/14958
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>