Move the matrix stage of SkLinearBitmapPipeline over to using SkSmallAllocator.

src/core/SkLinearBitmapPipeline_matrix.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_matrix_DEFINED
 #define SkLinearBitmapPipeline_matrix_DEFINED
 
 #include "SkLinearBitmapPipeline_core.h"
 
 namespace {
 class TranslateMatrixStrategy {
 public:
     TranslateMatrixStrategy(SkVector offset)
         : fXOffset{X(offset)}
         , fYOffset{Y(offset)} { }
 
-    void processPoints(Sk4s* xs, Sk4s* ys) {
+    void processPoints(Sk4s* xs, Sk4s* ys) const {
         *xs = *xs + fXOffset;
         *ys = *ys + fYOffset;
     }
 
     template <typename Next>
-    bool maybeProcessSpan(Span span, Next* next) {
+    bool maybeProcessSpan(Span span, Next* next) const {
         SkPoint start; SkScalar length; int count;
         std::tie(start, length, count) = span;
         next->pointSpan(Span{start + SkPoint{fXOffset, fYOffset}, length, count});
         return true;
     }
 
 private:
     const SkScalar fXOffset, fYOffset;
 };
 
 class ScaleMatrixStrategy {
 public:
     ScaleMatrixStrategy(SkVector offset, SkVector scale)
         : fXOffset{X(offset)}, fYOffset{Y(offset)}
         ,  fXScale{X(scale)},   fYScale{Y(scale)} { }
-    void processPoints(Sk4s* xs, Sk4s* ys) {
+    void processPoints(Sk4s* xs, Sk4s* ys) const {
         *xs = *xs * fXScale + fXOffset;
         *ys = *ys * fYScale + fYOffset;
     }
 
     template <typename Next>
-    bool maybeProcessSpan(Span span, Next* next) {
+    bool maybeProcessSpan(Span span, Next* next) const {
         SkPoint start; SkScalar length; int count;
         std::tie(start, length, count) = span;
         SkPoint newStart =
             SkPoint{X(start) * fXScale + fXOffset, Y(start) * fYScale + fYOffset};
         SkScalar newLength = length * fXScale;
         next->pointSpan(Span{newStart, newLength, count});
         return true;
     }
 
 private:
     const SkScalar fXOffset, fYOffset;
     const SkScalar fXScale,  fYScale;
 };
 
 class AffineMatrixStrategy {
 public:
     AffineMatrixStrategy(SkVector offset, SkVector scale, SkVector skew)
         : fXOffset{X(offset)}, fYOffset{Y(offset)}
         , fXScale{X(scale)},   fYScale{Y(scale)}
         , fXSkew{X(skew)},     fYSkew{Y(skew)} { }
-    void processPoints(Sk4s* xs, Sk4s* ys) {
+    void processPoints(Sk4s* xs, Sk4s* ys) const {
         Sk4s newXs = fXScale * *xs +  fXSkew * *ys + fXOffset;
         Sk4s newYs =  fYSkew * *xs + fYScale * *ys + fYOffset;
 
         *xs = newXs;
         *ys = newYs;
     }
 
     template <typename Next>
-    bool maybeProcessSpan(Span span, Next* next) {
+    bool maybeProcessSpan(Span span, Next* next) const {
         return false;
     }
 
 private:
     const SkScalar fXOffset, fYOffset;
     const SkScalar fXScale,  fYScale;
     const SkScalar fXSkew,   fYSkew;
 };
 
 class PerspectiveMatrixStrategy {
 public:
     PerspectiveMatrixStrategy(SkVector offset, SkVector scale, SkVector skew,
                               SkVector zSkew, SkScalar zOffset)
         : fXOffset{X(offset)}, fYOffset{Y(offset)}, fZOffset{zOffset}
         , fXScale{X(scale)},   fYScale{Y(scale)}
         , fXSkew{X(skew)},     fYSkew{Y(skew)}, fZXSkew{X(zSkew)}, fZYSkew{Y(zSkew)} { }
-    void processPoints(Sk4s* xs, Sk4s* ys) {
+    void processPoints(Sk4s* xs, Sk4s* ys) const {
         Sk4s newXs = fXScale * *xs +  fXSkew * *ys + fXOffset;
         Sk4s newYs =  fYSkew * *xs + fYScale * *ys + fYOffset;
         Sk4s newZs =  fZXSkew * *xs + fZYSkew * *ys + fZOffset;
 
         *xs = newXs / newZs;
         *ys = newYs / newZs;
     }
 
     template <typename Next>
-    bool maybeProcessSpan(Span span, Next* next) {
+    bool maybeProcessSpan(Span span, Next* next) const {
         return false;
     }
 
 private:
     const SkScalar fXOffset, fYOffset, fZOffset;
     const SkScalar fXScale,  fYScale;
     const SkScalar fXSkew,   fYSkew,   fZXSkew, fZYSkew;
 };
 
 
 }  // namespace
 
 #endif  // SkLinearBitmapPipeline_matrix_DEFINED