Add 8888 fast SrcOver mode.

src/core/SkLinearBitmapPipeline_sample.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 SkLinearBitmapPipeline_sampler_DEFINED
 #define SkLinearBitmapPipeline_sampler_DEFINED
 
@@ skipping 542 matching lines @@
                 x += dx;
                 count -= 1;
             }
         }
     }
 
     Next* const fNext;
     SourceStrategy fStrategy;
 };
 
-class sRGBFast {
-public:
-    static Sk4s VECTORCALL sRGBToLinear(Sk4s pixel) {
-        Sk4s l = pixel * pixel;
-        return Sk4s{l[0], l[1], l[2], pixel[3]};
-    }
-};
-
 enum class ColorOrder {
     kRGBA = false,
     kBGRA = true,
 };
 template <SkColorProfileType colorProfile, ColorOrder colorOrder>
 class Pixel8888 {
 public:
     Pixel8888(int width, const uint32_t* src) : fSrc{src}, fWidth{width}{ }
     Pixel8888(const SkPixmap& srcPixmap)
         : fSrc{srcPixmap.addr32()}
@@ skipping 203 matching lines @@
     const void* row(int y) { return fSrc + y * fWidth[0]; }
 
 private:
     const uint64_t* const fSrc;
     const Sk4i            fWidth;
 };
 
 }  // namespace
 
 #endif  // SkLinearBitmapPipeline_sampler_DEFINED