Move the matrix stage of SkLinearBitmapPipeline over to using SkSmallAllocator.

src/core/SkLinearBitmapPipeline.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_DEFINED
 #define SkLinearBitmapPipeline_DEFINED
 
 #include "SkColor.h"
 #include "SkImageInfo.h"
 #include "SkMatrix.h"
 #include "SkShader.h"
+#include "SkSmallAllocator.h"
 
 class SkEmbeddableLinearPipeline;
 
 enum SkGammaType {
     kLinear_SkGammaType,
     kSRGB_SkGammaType,
 };
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 // SkLinearBitmapPipeline - encapsulates all the machinery for doing floating point pixel
@@ skipping 93 matching lines @@
 
     };
 
     class PointProcessorInterface;
     class SampleProcessorInterface;
     class BlendProcessorInterface;
     class DestinationInterface;
     class PixelAccessorInterface;
 
     // These values were generated by the assert above in Stage::init{Sink|Stage}.
-    using MatrixStage  = Stage<PointProcessorInterface,     56, PointProcessorInterface>;
     using TileStage    = Stage<PointProcessorInterface,     48, SampleProcessorInterface>;
     using SampleStage  = Stage<SampleProcessorInterface,   160, BlendProcessorInterface>;
     using BlenderStage = Stage<BlendProcessorInterface,     48>;
     using Accessor     = PolyMemory<PixelAccessorInterface, 64>;
 
 private:
+    PointProcessorInterface* ChooseMatrix(
+        PointProcessorInterface* next,
+        const SkMatrix& inverse);
+
+    using MemoryAllocator = SkSmallAllocator<64, 1>;
+    using MatrixCloner =
+        std::function<PointProcessorInterface* (PointProcessorInterface*, MemoryAllocator*)>;
+
+    MemoryAllocator          fMemory;
     PointProcessorInterface* fFirstStage;
-    MatrixStage              fMatrixStage;
+    MatrixCloner             fMatrixStageCloner;
     TileStage                fTileStage;
     SampleStage              fSampleStage;
     BlenderStage             fBlenderStage;
     DestinationInterface*    fLastStage;
     Accessor                 fAccessor;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // SkEmbeddableLinearPipeline - manage stricter alignment needs for SkLinearBitmapPipeline.
 class SkEmbeddableLinearPipeline {
@@ skipping 16 matching lines @@
     }
     SkLinearBitmapPipeline& operator*()  const { return *this->get(); }
     SkLinearBitmapPipeline* operator->() const { return  this->get(); }
 
 private:
     alignas(SkLinearBitmapPipeline) mutable char fPipelineStorage[sizeof(SkLinearBitmapPipeline)];
     bool                                         fInitialized {false};
 };
 
 #endif  // SkLinearBitmapPipeline_DEFINED