Fix color xform width bug when scaling/subsetting

src/codec/SkSwizzler.h

Index: src/codec/SkSwizzler.h
diff --git a/src/codec/SkSwizzler.h b/src/codec/SkSwizzler.h
index 48450470486d54a5f54b0c3ec1d15a69ccf17dff..6172af5c433a69e14989a2a5ddde2d05d6650864 100644
--- a/src/codec/SkSwizzler.h
+++ b/src/codec/SkSwizzler.h
@@ -72,6 +72,12 @@ public:
      */
     int sampleX() const { return fSampleX; }
 
+    /**
+     *  Returns the actual number of pixels written to destination memory, taking
+     *  scaling, subsetting, and partial frames into account.
+     */
+    int swizzleWidth() const { return fSwizzleWidth; }
+
 private:
 
     /**