Update GrConfigConversionEffect to use an input FP.

In a strange twist, this effect already exposed a required input FP to
external callers, but implemented its behavior using RunInSeries. This
doesn't appear to have imparted any benefit, compared to sampling from
a child FP in the usual way.

Additionally, moved a 100-line test function `GrConfigConversionEffect::
TestForPreservingPMConversions` out of the header and into the CPP.

Change-Id: Ice8c1f1e2cb76177a8a2bf6cfc3e3d163854df64
Bug: skia:10217
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/300908
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
3 files changed