DM testing for skipping and scaling

dm/DMSrcSink.h

Index: dm/DMSrcSink.h
diff --git a/dm/DMSrcSink.h b/dm/DMSrcSink.h
index bd8c41ee186593dff1a58677b0be1e3a33e22be6..b7c28edf006f17e1c32504364c7d2456fff8d97a 100644
--- a/dm/DMSrcSink.h
+++ b/dm/DMSrcSink.h
@@ -98,13 +98,14 @@ public:
         kNormal_Mode,
         kScanline_Mode,
         kScanline_Subset_Mode,
+        kStripe_Mode, // Tests the skipping of scanlines
     };
     enum DstColorType {
         kGetFromCanvas_DstColorType,
         kIndex8_Always_DstColorType,
         kGrayscale_Always_DstColorType,
     };
-    CodecSrc(Path, Mode, DstColorType);
+    CodecSrc(Path, Mode, DstColorType, float);
 
     Error draw(SkCanvas*) const override;
     SkISize size() const override;
@@ -113,6 +114,7 @@ private:
     Path                   fPath;
     Mode                   fMode;
     DstColorType           fDstColorType;
+    float                  fScale;
 };