API change to allow for NormalSource selection at the user level.

src/core/SkNormalSource.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.
  */
 
 #ifndef SkNormalSource_DEFINED
 #define SkNormalSource_DEFINED
 
 #include "SkFlattenable.h"
 
-/** Abstract class that generates or reads in normals for use by SkLightingShader. Not to be
-    used as part of the API yet. Used internally by SkLightingShader.
+/** Abstract class that generates or reads in normals for use by SkLightingShader.
 */
 class SK_API SkNormalSource : public SkFlattenable {
 public:
     virtual ~SkNormalSource() override;
 
 #if SK_SUPPORT_GPU
     /** Returns a fragment processor that takes no input and outputs a normal (already rotated)
         as its output color. To be used as a child fragment processor.
     */
     virtual sk_sp<GrFragmentProcessor> asFragmentProcessor(
@@ skipping 17 matching lines @@
     /** Returns an instance of 'Provider' that provides normals for the CPU pipeline. The
         necessary data will be initialized in place at 'storage'.
     */
     virtual Provider* asProvider(const SkShader::ContextRec&, void* storage) const = 0;
 
     /** Amount of memory needed to store a provider object and its dependencies.
      */
     virtual size_t providerSize(const SkShader::ContextRec&) const = 0;
 
     /** Returns a normal source that provides normals sourced from the the normal map argument.
-        Not to be used as part of the API yet. Used internally by SkLightingShader.
 
-        @param  map              a shader that outputs the normal map
-        @param  normRotation     rotation applied to the normal map's normals, in the
-                                 [cos a, sin a] form.
+        @param  map  a shader that outputs the normal map
+        @param  ctm  the current canvas' total matrix, used to rotate normals when necessary.
 
         nullptr will be returned if 'map' is null
 
         The normal map is currently assumed to be an 8888 image where the normal at a texel
         is retrieved by:
             N.x = R-127;
             N.y = G-127;
             N.z = B-127;
             N.normalize();
         The +Z axis is thus encoded in RGB as (127, 127, 255) while the -Z axis is
         (127, 127, 0).
     */
-    static sk_sp<SkNormalSource> MakeFromNormalMap(sk_sp<SkShader> map,
-                                                   const SkVector& normRotation);
+    static sk_sp<SkNormalSource> MakeFromNormalMap(sk_sp<SkShader> map, const SkMatrix& ctm);
 
     SK_DEFINE_FLATTENABLE_TYPE(SkNormalSource)
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 };
 
 #endif