Fix quickReject computation for blurs

include/effects/SkBlurMaskFilter.h

Index: include/effects/SkBlurMaskFilter.h
===================================================================
--- include/effects/SkBlurMaskFilter.h	(revision 9604)
+++ include/effects/SkBlurMaskFilter.h	(working copy)
@@ -54,6 +54,22 @@
                                         SkScalar blurRadius);
 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
+
+    // This constant approximates the scaling done in the software path's
+    // "high quality" mode, in SkBlurMask::Blur() (1 / sqrt(3)).
+    // IMHO, it actually should be 1:  we blur "less" than we should do
+    // according to the CSS and canvas specs, simply because Safari does the same.
+    // Firefox used to do the same too, until 4.0 where they fixed it.  So at some
+    // point we should probably get rid of these scaling constants and rebaseline
+    // all the blur tests.
+    static const SkScalar kBLUR_SIGMA_SCALE;
+
+    // scale factor for the blur radius to match the behavior of the all existing blur
+    // code (both on the CPU and the GPU).  This magic constant is  1/sqrt(3).
+    // TODO: get rid of this fudge factor and move any required fudging up into
+    // the calling library
+    static const SkScalar kBlurRadiusFudgeFactor;
+
 private:
     SkBlurMaskFilter(); // can't be instantiated
 };