added in radial shadows

src/core/SkRadialShadowMapShader.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkReadBuffer.h"
+
+#ifndef SkRadialShadowMapShader_DEFINED
+#define SkRadialShadowMapShader_DEFINED
+
+#ifdef SK_EXPERIMENTAL_SHADOWING
+
+class SkLights;
+class SkShader;
+
+class SK_API SkRadialShadowMapShader {
+public:
+    /** This shader creates a 1D strip depth map for radial lights.
+     *  It can only take in 1 light to generate one shader at a time.
+     */
+    static sk_sp<SkShader> Make(sk_sp<SkShader> occluderShader,
+                                sk_sp<SkLights> light,
+                                int diffuseWidth, int diffuseHeight);
+
+    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+};
+
+#endif
+#endif