fix setPixelRef
fix setPixelRef

In setPixelRef()

If dx or dy are negative, assert in debug.
Pin pixel ref origin to account for dx and dy on right.
If colorType is unknown, ignore pr pixelref.
Set Bitmap rowbytes to match pixelref rowbytes.

In tryAllocPixels()

Return true early if colorType is unknown.

This assumes that the desired behavior is for Bitmaps
set to kUnknown_SkColorType to avoid allocating SkPixelRef
while avoiding debug asserts, which is what current
gm tests like BitmapCopy_extractSubset test for.

R=f5cabf8735907151a446812c9875d6c0c712d847@google.com

Change-Id: I0d36032d36a0b7dc111f4aff18c71382874fe1f5
Reviewed-on: https://skia-review.googlesource.com/53420
Reviewed-by: Mike Reed <f5cabf8735907151a446812c9875d6c0c712d847@google.com>
Commit-Queue: Cary Clark <52792aa984ff6c4e9c802c7fa3093ed6a52a791f@skia.org>

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