Abstracted diffuse color map out of SkLightingShaderImpl into a generic SkShader

src/core/SkLightingShader_NormalSource.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapProcShader.h"
 #include "SkBitmapProcState.h"
 #include "SkError.h"
@@ skipping 150 matching lines @@
 
     SkVector fInvNormRotation;
 };
 
 sk_sp<GrFragmentProcessor> NormalMapSourceImpl::asFragmentProcessor(
                                                      GrContext *context,
                                                      const SkMatrix &viewM,
                                                      const SkMatrix *localMatrix,
                                                      SkFilterQuality filterQuality,
                                                      SkSourceGammaTreatment gammaTreatment) const {
-
     sk_sp<GrFragmentProcessor> bitmapFP = fBitmapShader->asFragmentProcessor(context, viewM,
             localMatrix, filterQuality, gammaTreatment);
 
     return sk_make_sp<NormalMapFP>(std::move(bitmapFP), fInvNormRotation);
 }
 
 #endif // SK_SUPPORT_GPU
 
 ////////////////////////////////////////////////////////////////////////////
 
@@ skipping 89 matching lines @@
     this->INHERITED::flatten(buf);
 
     buf.writeFlattenable(fBitmapShader.get());
     buf.writePoint(fInvNormRotation);
 }
 
 ////////////////////////////////////////////////////////////////////////////
 
 sk_sp<SkLightingShader::NormalSource> SkLightingShader::NormalSource::MakeMap(
         const SkBitmap &normal, const SkVector &invNormRotation, const SkMatrix *normLocalM) {
-
     if (normal.isNull() || SkBitmapProcShader::BitmapIsTooBig(normal)) {
         return nullptr;
     }
 
     SkASSERT(SkScalarNearlyEqual(invNormRotation.lengthSqd(), SK_Scalar1));
 
     // TODO: support other tile modes
     sk_sp<SkShader> bitmapShader = SkMakeBitmapShader(normal, SkShader::kClamp_TileMode,
             SkShader::kClamp_TileMode, normLocalM, nullptr);
 
     return sk_make_sp<NormalMapSourceImpl>(std::move(bitmapShader), invNormRotation);
 }
 
 ////////////////////////////////////////////////////////////////////////////
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkLightingShader::NormalSource)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(NormalMapSourceImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
 
 ////////////////////////////////////////////////////////////////////////////