readpixels GM uses GPU image in GPU configs
readpixels GM uses GPU image in GPU configs

This now demonstrates that readPixels does not do color sapce conversion
in Ganesh (and fails completely for unpremul F16). Next: fix those issues.

BUG=skia:5853

Change-Id: If3bd1882249ae85b4738ef72e16cfb87b06b9363
Reviewed-on: https://skia-review.googlesource.com/9904
Commit-Queue: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>
Reviewed-by: Matt Sarett <bb43c9b8214fcf1292f134c9714ba8a0e7075913@google.com>

rubenvb/skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,google/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,google/skia,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,rubenvb/skia,google/skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,rubenvb/skia,HalCanary/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia