Correct sRGB <-> linear everywhere.

src/core/SkLinearBitmapPipeline_sample.h

Index: src/core/SkLinearBitmapPipeline_sample.h
diff --git a/src/core/SkLinearBitmapPipeline_sample.h b/src/core/SkLinearBitmapPipeline_sample.h
index e957ae7e4d0268cc285b193d0ceb2d31f9184d47..a8beadbda0939378712a77ef65c67b663b3d56c1 100644
--- a/src/core/SkLinearBitmapPipeline_sample.h
+++ b/src/core/SkLinearBitmapPipeline_sample.h
@@ -158,19 +158,9 @@ public:
 private:
     static const size_t kColorTableSize = sizeof(Sk4f[256]) + 12;
     Sk4f convertPixel(SkPMColor pmColor) {
-        Sk4f pixel = to_4f(pmColor);
-        float alpha = get_alpha(pixel);
-        if (alpha != 0.0f) {
-            float invAlpha = 1.0f / alpha;
-            Sk4f normalize = {invAlpha, invAlpha, invAlpha, 1.0f / 255.0f};
-            pixel = pixel * normalize;
-            if (gammaType == kSRGB_SkGammaType) {
-                pixel = linear_to_srgb(pixel);
-            }
-            return pixel;
-        } else {
-            return Sk4f{0.0f};
-        }
+        return swizzle_rb_if_bgra(
+            (gammaType == kSRGB_SkGammaType) ? Sk4f_fromS32(pmColor)
+                                             : Sk4f_fromL32(pmColor));
     }
     SkAutoMalloc         fColorTableStorage{kColorTableSize};
     Sk4f*                fColorTable;
@@ -183,11 +173,10 @@ public:
     PixelConverter(const SkPixmap& srcPixmap) { }
 
     Sk4f toSk4f(Element pixel) const {
-        float gray = pixel * (1.0f/255.0f);
-        Sk4f result = Sk4f{gray, gray, gray, 1.0f};
-        return gammaType == kSRGB_SkGammaType
-               ? srgb_to_linear(result)
-               : result;
+        float gray = (gammaType == kSRGB_SkGammaType)
+            ? sk_linear_from_srgb[pixel]
+            : pixel * (1/255.0f);
+        return {gray, gray, gray, 1.0f};
     }
 };