Refactoring of GPU NormalMap handling out into its own class

src/core/SkNormalSourceImpl.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 SkNormalSourceImpl_DEFINED
+#define SkNormalSourceImpl_DEFINED
+
+#include "SkBitmapProcState.h"
+#include "SkColor.h"
+#include "SkEmptyShader.h"
+#include "SkErrorInternals.h"
+#include "SkLightingShader.h"
+#include "SkMathPriv.h"
+#include "SkPoint3.h"
+#include "SkReadBuffer.h"
+#include "SkWriteBuffer.h"
+#include "SkNormalSourceImpl.h"
+#include "GrCoordTransform.h"
+#include "GrFragmentProcessor.h"
+#include "GrInvariantOutput.h"
+#include "GrTextureAccess.h"
+#include "glsl/GrGLSLFragmentProcessor.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
+#include "glsl/GrGLSLProgramDataManager.h"
+#include "glsl/GrGLSLUniformHandler.h"
+#include "SkGr.h"
+#include "SkGrPriv.h"
+
+// TODO change to flattenable
+class NormalSource : public SkRefCnt {
+
+public:
+
+    virtual ~NormalSource(){};
+
+    virtual const GrFragmentProcessor* asFragmentProcessor(
+                                                  GrContext* context,
+                                                  const SkMatrix& viewM,
+                                                  const SkMatrix* localMatrix,
+                                                  SkFilterQuality filterQuality,
+                                                  SkSourceGammaTreatment gammaTreatment) const = 0;
+};
+
+class NormalMapSource {
+public:
+    static sk_sp<NormalSource> Make(const SkBitmap& normal, const SkVector& invNormRotation,
+                                    const SkMatrix* normLocalM);
+};
+
+#endif