Srcover for sprite blitters.

src/core/SkLinearBitmapPipeline.h

Index: src/core/SkLinearBitmapPipeline.h
diff --git a/src/core/SkLinearBitmapPipeline.h b/src/core/SkLinearBitmapPipeline.h
index dce537aa6e6aa90f27f52667e468ee27a712a91a..b81632b089927a4730a538950a386e6e3f39cdff 100644
--- a/src/core/SkLinearBitmapPipeline.h
+++ b/src/core/SkLinearBitmapPipeline.h
@@ -22,6 +22,7 @@ class SkEmbeddableLinearPipeline;
 // class SkEmbeddableLinearPipeline below manages these requirements.
 class SkLinearBitmapPipeline {
 public:
+    // Constructor to support producing an SkBlitter.
     SkLinearBitmapPipeline(
         const SkMatrix& inverse,
         SkFilterQuality filterQuality,
@@ -29,6 +30,14 @@ public:
         SkColor paintColor,
         const SkPixmap& srcPixmap);
 
+    // Constructor to support producing an SkSpriteBlitter.
+    SkLinearBitmapPipeline(
+        SkPixmap& dstPixmap,
+        const SkPixmap& srcPixmap,
+        SkIPoint leftTop,
+        SkXfermode::Mode xferMode);
+
+    // Constructor to support producing an SkBlitter.
     SkLinearBitmapPipeline(
         const SkLinearBitmapPipeline& pipeline,
         const SkPixmap& srcPixmap,