check pm swizzle when extracting lcd coverage
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1706283005
Review URL: https://codereview.chromium.org/1706283005
diff --git a/src/core/SkXfermode4f.cpp b/src/core/SkXfermode4f.cpp
index bf30e92..b7f2913 100644
--- a/src/core/SkXfermode4f.cpp
+++ b/src/core/SkXfermode4f.cpp
@@ -427,7 +427,11 @@
#include "SkColorPriv.h"
static Sk4f lcd16_to_unit_4f(uint16_t rgb) {
+#ifdef SK_PMCOLOR_IS_RGBA
Sk4i rgbi = Sk4i(SkGetPackedR16(rgb), SkGetPackedG16(rgb), SkGetPackedB16(rgb), 0);
+#else
+ Sk4i rgbi = Sk4i(SkGetPackedB16(rgb), SkGetPackedG16(rgb), SkGetPackedR16(rgb), 0);
+#endif
return SkNx_cast<float>(rgbi) * Sk4f(1.0f/31, 1.0f/63, 1.0f/31, 0);
}