Add a color-spin control to Viewer
Add a color-spin control to Viewer

This cycles the primaries, just like SkColorSpace::makeColorSpin.
Helpful for debugging more exotic color space issues.

Change-Id: I3434c7a9f24642f13be0ac3513599a15247d1f6f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469360
Auto-Submit: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>
Commit-Queue: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>
Commit-Queue: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Reviewed-by: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>
Reviewed-by: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>

aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia