Create swizzle table inside of glsl caps

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/4036674952f341dab0695c3b054fefa5bb8cdec1

Review URL: https://codereview.chromium.org/1420033005
diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index 6893dc7..9287556 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -100,6 +100,7 @@
     PrecisionInfo fFloatPrecisions[kGrShaderTypeCount][kGrSLPrecisionCount];
 
 private:
+    virtual void onApplyOptionsOverrides(const GrContextOptions&) {};
     typedef SkRefCnt INHERITED;
 };
 
@@ -274,6 +275,8 @@
     bool fConfigTextureSupport[kGrPixelConfigCnt];
 
 private:
+    virtual void onApplyOptionsOverrides(const GrContextOptions&) {};
+
     bool fSupressPrints : 1;
     bool fDrawPathMasksToCompressedTextureSupport : 1;