Changed SkLightingShader API to take in a shader as color source

src/core/SkLightingShader.h

 /*
  * 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 SkLightingShader_DEFINED
 #define SkLightingShader_DEFINED
 
 #include "SkLights.h"
 #include "SkShader.h"
 
 class SkBitmap;
 class SkMatrix;
 class SkNormalSource;
 
 class SK_API SkLightingShader {
 public:
-    /** Returns a shader that lights the diffuse map using the normals and a set of lights.
+    /** Returns a shader that lights the shape, colored by the diffuseShader, using the
+        normals from normalSource, with the set of lights provided.
 
         It returns a shader with a reference count of 1.
         The caller should decrement the shader's reference count when done with the shader.
         It is an error for count to be < 2.
-        @param  diffuse     the diffuse bitmap
-        @param  lights       the lights applied to the normal map
-        @param  diffLocalMatrix the local matrix for the diffuse map (transform from
-                                texture coordinates to shape source coordinates). nullptr is
-                                interpreted as an identity matrix.
-        @param  normalSource the source for the normals
-
-        nullptr will be returned if:
-            'diffuse' is empty
-            'diffuse' is too big (> 65535 on any side)
+        @param  diffuseShader     the shader that provides the colors
+        @param  normalSource      the source for the shape's normals
+        @param  lights            the lights applied to the normals
 
         The lighting equation is currently:
             result = LightColor * DiffuseColor * (Normal * LightDir) + AmbientColor
 
     */
-    static sk_sp<SkShader> Make(const SkBitmap& diffuse, sk_sp<SkLights> lights,
-                                const SkMatrix* diffLocalMatrix,
-                                sk_sp<SkNormalSource> normalSource);
+    static sk_sp<SkShader> Make(sk_sp<SkShader> diffuseShader, sk_sp<SkNormalSource> normalSource,
+                                sk_sp<SkLights> lights);
 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 };
 
 #endif