adding new GM to demostrate new shadows

src/core/SkShadowShader.h

Index: src/core/SkShadowShader.h
diff --git a/src/core/SkShadowShader.h b/src/core/SkShadowShader.h
new file mode 100644
index 0000000000000000000000000000000000000000..2d6870ca10e3a4eb8ca2812112f93fbfe152a678
--- /dev/null
+++ b/src/core/SkShadowShader.h
@@ -0,0 +1,31 @@
+/*

[robertphillips, 2016/07/26 16:15:06]

2016

[vjiaoblack, 2016/07/27 15:26:28]

Done.

+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkShadowShader_DEFINED
+#define SkShadowShader_DEFINED
+

[robertphillips, 2016/07/26 16:15:06]

Do we actually need these two includes or can we just predeclare them ?

[vjiaoblack, 2016/07/27 15:26:28]

Done.

+#include "SkLights.h"
+#include "SkShader.h"
+

[robertphillips, 2016/07/26 16:15:06]

Do we actually need the SkBitmap & SkMatrix predeclarations ?

[vjiaoblack, 2016/07/27 15:26:28]

Done.

+class SkBitmap;
+class SkMatrix;
+class SkNormalSource;
+
+class SK_API SkShadowShader {
+public:
+    /** Returns a shader that lights the shape, colored by the diffuseShader, using the
+        normals from normalSource, with the set of lights provided.
+    */
+    static sk_sp<SkShader> Make(sk_sp<SkShader> povDepthShader,

[robertphillips, 2016/07/26 16:15:06]

just diffuseShader (no 2) ?

[vjiaoblack, 2016/07/27 15:26:28]

Done.

+                                sk_sp<SkShader> diffuseShader2,
+//                                sk_sp<SkNormalSource> normalSource,
+                                sk_sp<SkLights> lights);
+
+    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+};
+
+#endif