Centralize decision about whether to do bicubic filtering, and fallbacks to mip, bilerp, or nearest

src/gpu/effects/GrBicubicEffect.h

Index: src/gpu/effects/GrBicubicEffect.h
diff --git a/src/gpu/effects/GrBicubicEffect.h b/src/gpu/effects/GrBicubicEffect.h
index cc8b1208634d76a2627f6d8c4f5946a6bb2ff7b8..1998e68780c18a7bc213ae1313c60df77cda69cd 100644
--- a/src/gpu/effects/GrBicubicEffect.h
+++ b/src/gpu/effects/GrBicubicEffect.h
@@ -78,6 +78,16 @@ public:
         return CreateEffectRef(effect);
     }
 
+    /**
+     * Determines whether the bicubic effect should be used based on the transformation from the
+     * local coords to the device. Returns true if the bicubic effect should be used. filterMode
+     * is set to appropriate filtering mode to use regardless of the return result (e.g. when this
+     * returns false it may indicate that the best fallback is to use kMipMap, kBilerp, or
+     * kNearest).
+     */
+    static bool ShouldUseBicubic(const SkMatrix& localCoordsToDevice,
+                                 GrTextureParams::FilterMode* filterMode);
+
 private:
     GrBicubicEffect(GrTexture*, const SkScalar coefficients[16],
                     const SkMatrix &matrix, const SkShader::TileMode tileModes[2]);