make the filter mode for GrTextureAccess an enum so we can plumb down

src/gpu/effects/GrSingleTextureEffect.cpp

Index: src/gpu/effects/GrSingleTextureEffect.cpp
diff --git a/src/gpu/effects/GrSingleTextureEffect.cpp b/src/gpu/effects/GrSingleTextureEffect.cpp
index 0c671f16d039450aafc9e868fa6f36e7ba22a548..532ce04217bebda26dbc5384389b3fc7536340b3 100644
--- a/src/gpu/effects/GrSingleTextureEffect.cpp
+++ b/src/gpu/effects/GrSingleTextureEffect.cpp
@@ -18,9 +18,9 @@ GrSingleTextureEffect::GrSingleTextureEffect(GrTexture* texture,
 
 GrSingleTextureEffect::GrSingleTextureEffect(GrTexture* texture,
                                              const SkMatrix& m,
-                                             bool bilerp,
+                                             GrTextureParams::FilterMode filterMode,
                                              CoordsType coordsType)
-    : fTextureAccess(texture, bilerp)
+    : fTextureAccess(texture, filterMode)
     , fMatrix(m)
     , fCoordsType(coordsType) {
     this->addTextureAccess(&fTextureAccess);