Fix quickReject computation for blurs

include/effects/SkBlurMaskFilter.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBlurMaskFilter_DEFINED
 #define SkBlurMaskFilter_DEFINED
 
@@ skipping 36 matching lines @@
         @param ambient      0...1 amount of ambient light
         @param specular     coefficient for specular highlights (e.g. 8)
         @param blurRadius   amount to blur before applying lighting (e.g. 3)
         @return the emboss maskfilter
     */
     static SkMaskFilter* CreateEmboss(  const SkScalar direction[3],
                                         SkScalar ambient, SkScalar specular,
                                         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
 };
 
 #endif