Add SkSpecialImage::extractSubset & NewFromPixmap

This is calved off of: https://codereview.chromium.org/1785643003/ (Switch SkBlurImageFilter over to new onFilterImage interface)

This now relies on: https://codereview.chromium.org/1813483002/ (ImagePixelLocker now manually allocates SkPixmap) to clean up the uses of SkAutoPixmapStorage in Chromium

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1787883002

Committed: https://skia.googlesource.com/skia/+/250581493a0859987e482810879e85e5ac2dc002

Review URL: https://codereview.chromium.org/1787883002
diff --git a/src/gpu/GrSWMaskHelper.h b/src/gpu/GrSWMaskHelper.h
index b90205b..fb5d9e8 100644
--- a/src/gpu/GrSWMaskHelper.h
+++ b/src/gpu/GrSWMaskHelper.h
@@ -8,6 +8,7 @@
 #ifndef GrSWMaskHelper_DEFINED
 #define GrSWMaskHelper_DEFINED
 
+#include "SkAutoPixmapStorage.h"
 #include "GrColor.h"
 #include "GrPipelineBuilder.h"
 #include "SkBitmap.h"