Add a SkPixelSerializer SkImage encode variant

include/core/SkImage.h

Index: include/core/SkImage.h
diff --git a/include/core/SkImage.h b/include/core/SkImage.h
index 5b9e2031758f8ebc317041289a0603f8113d1ece..008ce2447a0b2f3bfe6cf31edd085706ac0a45e3 100644
--- a/include/core/SkImage.h
+++ b/include/core/SkImage.h
@@ -21,6 +21,7 @@ class SkColorTable;
 class SkImageGenerator;
 class SkPaint;
 class SkPicture;
+class SkPixelSerializer;
 class SkString;
 class SkSurface;
 class SkSurfaceProps;
@@ -223,6 +224,11 @@ public:
      */
     SkData* encode(SkImageEncoder::Type, int quality) const;
 
+    /**
+     *  Same as the above, but using the SkPixelSerializer.

[reed1, 2015/09/02 13:59:57]

// Can the serialize be null?
// What happens if the serializer returns false?

+     */
+    SkData* encode(SkPixelSerializer*) const;
+
     SkData* encode() const {
         return this->encode(SkImageEncoder::kPNG_Type, 100);
     }