WIP: runtime switch for how to interpret SkColor -vs- srgb

src/core/SkColor.cpp

Index: src/core/SkColor.cpp
diff --git a/src/core/SkColor.cpp b/src/core/SkColor.cpp
index ab6330011978610a999ca1effe02161cbf495ad8..1c6f0b65792e91b0591c8e711d1a37e7edd590ab 100644
--- a/src/core/SkColor.cpp
+++ b/src/core/SkColor.cpp
@@ -9,6 +9,8 @@
 #include "SkColorPriv.h"
 #include "SkFixed.h"
 
+bool gTreatSkColorAsSRGB;
+
 SkPMColor SkPreMultiplyARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
     return SkPremultiplyARGBInline(a, r, g, b);
 }
@@ -156,6 +158,11 @@ SkColor4f SkColor4f::FromColor(SkColor c) {
     Sk4f value = SkNx_shuffle<3,2,1,0>(SkNx_cast<float>(Sk4b::Load(&c)));
     SkColor4f c4;
     (value * Sk4f(1.0f / 255)).store(&c4);
+    if (gTreatSkColorAsSRGB) {
+        c4.fR = srgb_to_linear(c4.fR);
+        c4.fG = srgb_to_linear(c4.fG);
+        c4.fB = srgb_to_linear(c4.fB);
+    }
     return c4;
 }