move declaration of CreateLightingFilter into SkColorMatrixFilter

include/effects/SkColorMatrixFilter.h

 /*
  * Copyright 2007 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkColorMatrixFilter_DEFINED
 #define SkColorMatrixFilter_DEFINED
 
 #include "SkColorFilter.h"
 #include "SkColorMatrix.h"
 
 class SK_API SkColorMatrixFilter : public SkColorFilter {
 public:
     static SkColorFilter* Create(const SkColorMatrix& cm) {
         return new SkColorMatrixFilter(cm);
     }
     static SkColorFilter* Create(const SkScalar array[20]) {
         return new SkColorMatrixFilter(array);
     }
 
+    /**
+     *  Create a colorfilter that multiplies the RGB channels by one color, and
+     *  then adds a second color, pinning the result for each component to
+     *  [0..255]. The alpha components of the mul and add arguments
+     *  are ignored.
+     */
+    static SkColorFilter* CreateLightingFilter(SkColor mul, SkColor add);
+
     void filterSpan(const SkPMColor src[], int count, SkPMColor[]) const override;
     uint32_t getFlags() const override;
     bool asColorMatrix(SkScalar matrix[20]) const override;
     SkColorFilter* newComposed(const SkColorFilter*) const override;
 
 #if SK_SUPPORT_GPU
     const GrFragmentProcessor* asFragmentProcessor(GrContext*) const override;
 #endif
 
     SK_TO_STRING_OVERRIDE()
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkColorMatrixFilter)
 
 protected:
     explicit SkColorMatrixFilter(const SkColorMatrix&);
     explicit SkColorMatrixFilter(const SkScalar array[20]);
     void flatten(SkWriteBuffer&) const override;
 
 private:
     SkColorMatrix   fMatrix;
     float           fTranspose[SkColorMatrix::kCount]; // for Sk4s
     uint32_t        fFlags;
 
     void initState(const SkScalar array[20]);
 
     typedef SkColorFilter INHERITED;
 };
 
 #endif