Added API for Bevel NormalSource.

src/core/SkNormalSource.h

Index: src/core/SkNormalSource.h
diff --git a/src/core/SkNormalSource.h b/src/core/SkNormalSource.h
index e46e2dae34cc84d5fdf0e2877f2c21968f1fff13..e87003e4c22ec10f9371c8b60ecebbcb67fd0f5d 100644
--- a/src/core/SkNormalSource.h
+++ b/src/core/SkNormalSource.h
@@ -69,6 +69,20 @@ public:
     */
     static sk_sp<SkNormalSource> MakeFlat();
 
+    enum class BevelType {
+        kLinear,
+        kRoundedOut,
+        kRoundedIn
+    };
+    /** Returns a normal source that generates a bevel for the given shape. UNIMPLEMENTED: Will
+        return straight-up normals only.
+
+        @param  type   the type of bevel to add
+        @param  width  the width of the bevel, in source space
+        @param  height the height of the plateau, in source space
+    */
+    static sk_sp<SkNormalSource> MakeBevel(BevelType, SkScalar width, SkScalar height);
+
     SK_DEFINE_FLATTENABLE_TYPE(SkNormalSource)
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 };