Add flag to gradients to interpolate colors in premul space. Experimental API to encapsulate the sh…

Add flag to gradients to interpolate colors in premul space. Experimental API to encapsulate the shared parameters for all gradients into a struct.

BUG=
R=bsalomon@google.com

Committed: https://code.google.com/p/skia/source/detail?r=9273

[reed1, 2013-05-23 15:41:48]

have not yet plumbed it into radial, etc. just wanted to first review
- actual impl
- idea of Rec (or other name) for parameter clumping

[bsalomon, 2013-05-23 17:29:46]

On 2013/05/23 15:41:48, reed1 wrote:
> have not yet plumbed it into radial, etc. just wanted to first review
> - actual impl
> - idea of Rec (or other name) for parameter clumping

I'm not so sure about the new helper struct... I'd feel better if all the fields
were initialized in the constructor for the non-simple version.

[reed1, 2013-05-23 17:43:29]

may leave in Descriptor, but just for looks for now

[reed1, 2013-05-23 17:49:22]

PTAL

[bsalomon, 2013-05-23 17:50:55]

On 2013/05/23 17:49:22, reed1 wrote:
> PTAL

lgtm

[reed1, 2013-05-23 21:30:59]

all of our gms draw wacky when run in release mode :( . at least 3 of the 4
pixels in the dither suffer from this. dunno why yet.

[reed1, 2013-05-23 21:37:16]

patch #7 fixes release mode
PTAL

[bsalomon, 2013-05-24 12:30:19]

On 2013/05/23 21:37:16, reed1 wrote:
> patch #7 fixes release mode
> PTAL

lgtm (ugh)

[reed1, 2013-05-24 14:58:50]

Committed patchset #8 manually as r9273 (presubmit successful).