Propagate premultiplied color enforcement flag

The SkArithmeticMode_gpu GL filters support clamping to valid
premultiplied colors, however the flag for whether or not to do this,
which is present in their parent filters, is dropped when creating the
GL implementations. This change adds logic to forward the value from
the parent filter to the GL implementation.

This makes GPU behavior match software and fixes a WebKit
LayoutTest. See referenced bug.

BUG=473186
Committed: https://skia.googlesource.com/skia/+/af96fce87937aba4aa5d394ee6316ba790308490

[ericrk, 2015-10-15 19:06:00]

ericrk@chromium.org changed reviewers:
+ bsalomon@google.com, senorblanco@google.com

[Stephen White, 2015-10-15 19:49:37]

Good catch!

Could you add a test case to gm/xfermodeimagefilter?

(You might have to start a new row and embiggen the HEIGHT value.

[bsalomon, 2015-10-15 19:50:06]

seems ok to me, but leave final 1gtm to Stephen. Style nit, we use camel case
for param names.

[Stephen White, 2015-10-15 19:52:03]

Whoops, forgot this is actually an SkXfermode, not an SkXfermodeImageFilter.

Please add a test case or two to gm/arithmode.cpp.

[ericrk, 2015-10-19 21:19:44]

Patchset #2 (id:20001) has been deleted

[ericrk, 2015-10-19 21:21:29]

On 2015/10/15 19:52:03, Stephen White wrote:
> Whoops, forgot this is actually an SkXfermode, not an SkXfermodeImageFilter.
> 
> Please add a test case or two to gm/arithmode.cpp.

Added a couple test rows to gm/arithmode.cpp. Let me know how this looks.

I assume I have to just triage a gold failure after submission right? I don't
check in the new master now?

[Stephen White, 2015-10-19 21:30:25]

On 2015/10/19 21:21:29, ericrk wrote:
> On 2015/10/15 19:52:03, Stephen White wrote:
> > Whoops, forgot this is actually an SkXfermode, not an SkXfermodeImageFilter.
> > 
> > Please add a test case or two to gm/arithmode.cpp.
> 
> Added a couple test rows to gm/arithmode.cpp. Let me know how this looks.
> 
> I assume I have to just triage a gold failure after submission right? I don't
> check in the new master now?

That's right. Land the code change, and followup with triage at gold.skia.org.

[Stephen White, 2015-10-19 21:31:07]

senorblanco@chromium.org changed reviewers:
+ senorblanco@chromium.org

[Stephen White, 2015-10-19 21:31:08]

LGTM (but will probably need Brian's for the API change)

[Stephen White, 2015-10-19 21:31:41]

On 2015/10/19 21:31:08, Stephen White wrote:
> LGTM (but will probably need Brian's for the API change)

(never mind -- no API change means we should be able to CQ this)

[Stephen White, 2015-10-19 21:31:45]

The CQ bit was checked by senorblanco@chromium.org

[commit-bot: I haz the power, 2015-10-19 21:31:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1410553002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1410553002/60001

[commit-bot: I haz the power, 2015-10-19 21:41:13]

Committed patchset #3 (id:60001) as
https://skia.googlesource.com/skia/+/af96fce87937aba4aa5d394ee6316ba790308490