Builder class for SkLayerDrawLooper.

include/effects/SkLayerDrawLooper.h

Index: include/effects/SkLayerDrawLooper.h
diff --git a/include/effects/SkLayerDrawLooper.h b/include/effects/SkLayerDrawLooper.h
index 6955192b53f2e6f9edeb94f49efd0858a8a73b2b..761f6c9ca7dd69f6c7f81532bde0e868fe170258 100644
--- a/include/effects/SkLayerDrawLooper.h
+++ b/include/effects/SkLayerDrawLooper.h
@@ -134,6 +134,48 @@ private:
     };
 
     typedef SkDrawLooper INHERITED;
+
+public:
+    class SK_API Builder {
+    public:
+        Builder();
+        ~Builder();
+
+        /**
+         *  Call for each layer you want to add (from top to bottom).
+         *  This returns a paint you can modify, but that ptr is only valid until
+         *  the next call made to addLayer().
+         */
+        SkPaint* addLayer(const LayerInfo&);
+
+        /**
+         *  This layer will draw with the original paint, at the specified offset
+         */
+        void addLayer(SkScalar dx, SkScalar dy);
+
+        /**
+         *  This layer will with the original paint and no offset.
+         */
+        void addLayer() { this->addLayer(0, 0); }
+
+        /// Similar to addLayer, but adds a layer to the top.
+        SkPaint* addLayerOnTop(const LayerInfo&);
+
+        /**
+          * Pass list of layers on to newly built looper and return it. This will
+          * also reset the builder, so it can be used to build another looper.
+          */
+        SkLayerDrawLooper* detachLooper();
+
+    private:
+        Rec* fRecs;
+        Rec* fTopRec;
+        int  fCount;
+
+        void initLooperAndReset(SkLayerDrawLooper* looper);
+
+        friend class SkLayerDrawLooper;
+    };
 };
 
 #endif