udpate dox for colorfilter fragment processor requirements

udpate dox for colorfilter fragment processor requirements

BUG=skia:
NOTRY=True

Committed: https://skia.googlesource.com/skia/+/b7affb56bb295d52e543d6f0e45ba45acf42dcd6

[reed1, 2015-03-04 21:09:10]

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

[reed1, 2015-03-04 21:25:14]

ptal

[reed1, 2015-03-04 21:25:19]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-03-04 21:26:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/961933003/1

[commit-bot: I haz the power, 2015-03-04 21:26:20]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-03-05 03:26 UTC

[Stephen White, 2015-03-04 21:28:45]

LGTM.

Although it might be an interesting optimization to skip the
remultiply/unpremultiply where possible. I guess we'd have to provide a way for
a frag processor to request unpremultiplied colors from the previous processor.

[commit-bot: I haz the power, 2015-03-04 21:30:53]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/b7affb56bb295d52e543d6f0e45ba45acf42dcd6

[reed1, 2015-03-04 22:08:43]

On 2015/03/04 21:28:45, Stephen White wrote:
> LGTM.
> 
> Although it might be an interesting optimization to skip the
> remultiply/unpremultiply where possible. I guess we'd have to provide a way
for
> a frag processor to request unpremultiplied colors from the previous
processor.

Sure. If ganesh wants more flexibility when communicating pre-post requirements
in its stages, that's obviously fine by me.