Refactoring of GPU NormalMap handling out into its own class

src/core/SkBitmapProcShader.h

 /*
  * Copyright 2006 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 SkBitmapProcShader_DEFINED
 #define SkBitmapProcShader_DEFINED
 
 #include "SkShader.h"
 #include "SkSmallAllocator.h"
 
 struct SkBitmapProcState;
 class SkBitmapProvider;
 
 class SkBitmapProcShader : public SkShader {
 public:
     SkBitmapProcShader(const SkBitmap& src, TileMode tx, TileMode ty,
                        const SkMatrix* localMatrix = nullptr);
 
     bool isOpaque() const override;
 
+    // SkBitmapProcShader stores bitmap coordinates in a 16bit buffer, as it
+    // communicates between its matrix-proc and its sampler-proc. Until we can
+    // widen that, we have to reject bitmaps that are larger.
+    static bool BitmapIsTooBig(const SkBitmap&);
+
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBitmapProcShader)
 
 #if SK_SUPPORT_GPU
     sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext*, const SkMatrix& viewM,
                                                    const SkMatrix*, SkFilterQuality,
                                                    SkSourceGammaTreatment) const override;
 #endif
 
 protected:
@@ skipping 25 matching lines @@
 // Note that some contexts may contain other contexts (e.g. for compose shaders), but we've not
 // yet found a situation where the size below isn't big enough.
 typedef SkSmallAllocator<3, kSkBlitterContextSize> SkTBlitterAllocator;
 
 // If alloc is non-nullptr, it will be used to allocate the returned SkShader, and MUST outlive
 // the SkShader.
 sk_sp<SkShader> SkMakeBitmapShader(const SkBitmap& src, SkShader::TileMode, SkShader::TileMode,
                                    const SkMatrix* localMatrix, SkTBlitterAllocator* alloc);
 
 #endif