Move morphology GPU implementation into SkMorphologyimageFilter

This is (as much as possible) a straight code move from GrContext and GrMorphologyEffect.* into SkMorphologyImageFilter.cpp.

[bsalomon, 2012-08-02 14:21:58]

Overall looks good. Two things:

1) Should we have a mechanism for the SkGpuDevice to do a save of the GrContext
state prior to calling onFilterImageGPU?  It seems like we're being very
trusting of that function not having side effects.

2) I just landed the SK_SUPPORT_GPU change at r4912. So you may need to update
this a bit. You can test the build by setting GYP_DEFINES=skia_gpu=0 before
running gyp_skia. There isn't a bot yet, but will be soon.

[bsalomon, 2012-08-22 19:55:01]

LGTM.  Do you think we need something like onFilterImageGPU() for SkMaskFilter
so that we can do the same type of refactor for blur?

[Stephen White, 2012-08-22 20:01:17]

On 2012/08/22 19:55:01, bsalomon wrote:
> LGTM.  Do you think we need something like onFilterImageGPU() for SkMaskFilter
> so that we can do the same type of refactor for blur?

Interesting idea.  We'd need to share the setup code between the mask filter and
the image filter somehow too.

[Stephen White, 2012-08-22 21:31:52]

Landed as r5241; closing.