Revert of Make GrGammaEffect have explicit sRGB modes, plus exponential mode.

src/gpu/GrContext.cpp

Index: src/gpu/GrContext.cpp
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 4235ae85524ab36d9ffc4426d0e00a3d4548aa33..443494073af596a9ac0f9fee05d49be897d7478c 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -550,9 +550,12 @@
     }
 
     GrPaint paint;
-    paint.addColorTextureProcessor(src, GrCoordTransform::MakeDivByTextureWHMatrix(src));
-    if (!SkScalarNearlyEqual(gamma, 1.0f)) {
-        paint.addColorFragmentProcessor(GrGammaEffect::Create(gamma))->unref();
+    if (SkScalarNearlyEqual(gamma, 1.0f)) {
+        paint.addColorTextureProcessor(src, GrCoordTransform::MakeDivByTextureWHMatrix(src));
+    } else {
+        SkAutoTUnref<const GrFragmentProcessor> fp;
+        fp.reset(GrGammaEffect::Create(src, gamma));
+        paint.addColorFragmentProcessor(fp);
     }
     paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
     paint.setGammaCorrect(true);