Fix SkPixelXorXfermode serialization bug

src/effects/SkPixelXorXfermode.cpp

Index: src/effects/SkPixelXorXfermode.cpp
diff --git a/src/effects/SkPixelXorXfermode.cpp b/src/effects/SkPixelXorXfermode.cpp
index a9316cc55e4660492bbbbd346a6964fda87b48b2..e0ae146dda5886a4e74d14b0a29b4c08245c0c6b 100644
--- a/src/effects/SkPixelXorXfermode.cpp
+++ b/src/effects/SkPixelXorXfermode.cpp
@@ -21,7 +21,9 @@ SkPMColor SkPixelXorXfermode::xferColor(SkPMColor src, SkPMColor dst) const {
 }
 
 void SkPixelXorXfermode::flatten(SkWriteBuffer& wb) const {
-    wb.writeColor(fOpColor);
+    wb.writeColor(SkColorSetRGB(SkGetPackedR32(fOpColor),
+                                SkGetPackedG32(fOpColor),
+                                SkGetPackedB32(fOpColor)));
 }
 
 SkFlattenable* SkPixelXorXfermode::CreateProc(SkReadBuffer& buffer) {