Make all color xforms 'fast' (step 1)

src/core/SkColorSpaceXform.h

Index: src/core/SkColorSpaceXform.h
diff --git a/src/core/SkColorSpaceXform.h b/src/core/SkColorSpaceXform.h
index 723dea433570690a32850a2fe8c527cb777239e0..e09a7252ba5c376d37a8797d6aa46255cffb333d 100644
--- a/src/core/SkColorSpaceXform.h
+++ b/src/core/SkColorSpaceXform.h
@@ -34,16 +34,27 @@ public:
     virtual ~SkColorSpaceXform() {}
 };
 
-template <SkColorSpace::GammaNamed Src, SkColorSpace::GammaNamed Dst>
+template <SkColorSpace::GammaNamed Dst>
 class SkFastXform : public SkColorSpaceXform {
 public:
 
     void xform_RGB1_8888(uint32_t* dst, const uint32_t* src, uint32_t len) const override;
 
 private:
-    SkFastXform(const SkMatrix44& srcToDst);
+    SkFastXform(const sk_sp<SkColorSpace>& srcSpace, const SkMatrix44& srcToDst,
+                const sk_sp<SkColorSpace>& dstSpace);
 
-    float fSrcToDst[12];
+    static constexpr int kDstGammaTableSize = 1024;
+
+    // May contain pointers into storage or pointers into precomputed tables.
+    const float*         fSrcGammaTables[3];
+    float                fSrcGammaTableStorage[3 * 256];
+
+    float                fSrcToDst[12];
+
+    // May contain pointers into storage or pointers into precomputed tables.
+    const uint8_t*       fDstGammaTables[3];
+    uint8_t              fDstGammaTableStorage[3 * kDstGammaTableSize];
 
     friend class SkColorSpaceXform;
 };