SkGpuBlurUtils::GaussianBlur handles degenerate downscale cases.
SkGpuBlurUtils::GaussianBlur handles degenerate downscale cases.

Previously it aborted if at a downscale to 1 pixel the effective
sigma was greater than the max sigma.

For repeat/mirror the single col/row is the blurred result

For decal/clamp add a border of transparent/original border and then
recurse.

Bug: skia:11735
Bug: chromium:1174354

Change-Id: I3438f49fdc5167f6def61a49f9fc8eaef3912ec3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/385279
Commit-Queue: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>
Reviewed-by: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>

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