SkLiteDL: drawAsLayer()

This more or less the API you were thinking?

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2315283002

Review-Url: https://codereview.chromium.org/2315283002
diff --git a/src/core/SkLiteDL.h b/src/core/SkLiteDL.h
index 9dd1568..8edd700 100644
--- a/src/core/SkLiteDL.h
+++ b/src/core/SkLiteDL.h
@@ -27,6 +27,13 @@
     void setDrawFilter(SkDrawFilter*);
 #endif
 
+    // Draws as if...
+    //   SkRect bounds = this->getBounds();
+    //   canvas->saveLayer(&bounds, paint);
+    //       this->draw(canvas, matrix);
+    //   canvas->restore();
+    void drawAsLayer(SkCanvas*, const SkMatrix*, const SkPaint*);
+
     void save();
     void saveLayer(const SkRect*, const SkPaint*, const SkImageFilter*, SkCanvas::SaveLayerFlags);
     void restore();