Refactoring of CPU NormalMap handling out into its own class

src/core/SkLightingShader.h

Index: src/core/SkLightingShader.h
diff --git a/src/core/SkLightingShader.h b/src/core/SkLightingShader.h
index 6301eeeea13595919e5626829ac36134e93ccbe3..75a7738755865704972e22bc1c7232bb93764adf 100644
--- a/src/core/SkLightingShader.h
+++ b/src/core/SkLightingShader.h
@@ -16,9 +16,8 @@ class SkMatrix;
 
 class SK_API SkLightingShader {
 public:
-    /** Abstract class that generates or reads in normals for use by SkLightingShader. Currently
-        implements the GPU side only. 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. Not to be
+        used as part of the API yet. Used internally by SkLightingShader.
     */
     class NormalSource : public SkFlattenable {
     public:
@@ -37,6 +36,30 @@ public:
                 SkSourceGammaTreatment gammaTreatment) const = 0;
 #endif
 
+        class Provider {
+        public:
+            virtual ~Provider(){};

[egdaniel, 2016/06/16 13:48:10]

nit: space between () and {}

[dvonbeck, 2016/06/16 22:05:40]

Done.

+
+            /** Called for each span of the object being drawn on the CPU. Your subclass should set
+                the appropriate normals that correspond to the specified device coordinates.
+            */
+            virtual void fillScanLine(int x, int y, SkPoint3 output[], int count) const = 0;
+
+            /** Returns the maximum count that can be passed into 'fillScanLine' for an output
+                buffer of size 'count'.
+            */
+            virtual int maxCountForFillScanLine(int count) const = 0;
+        };
+
+        /** 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& rec, void* storage) const = 0;
+
+        /** Amount of memory needed to store a provider object and its dependencies.
+         */
+        virtual size_t providerSize() const = 0;
+
         SK_DEFINE_FLATTENABLE_TYPE(NormalSource)
     };