Ensure the Gaussian tail of circle blurs goes to zero.

src/effects/GrCircleBlurFragmentProcessor.cpp

Index: src/effects/GrCircleBlurFragmentProcessor.cpp
diff --git a/src/effects/GrCircleBlurFragmentProcessor.cpp b/src/effects/GrCircleBlurFragmentProcessor.cpp
index f319e3d90fc1863805b44be9d784c1b07a1b478c..c2d27c77373c02b09cbf33c5e36148d8c4a61cef 100644
--- a/src/effects/GrCircleBlurFragmentProcessor.cpp
+++ b/src/effects/GrCircleBlurFragmentProcessor.cpp
@@ -186,7 +186,7 @@ static inline void compute_profile_offset_and_size(float halfWH, float sigma,
         // blurred circle is solid.
         *offset = halfWH - 3 * sigma; // This location maps to 0.5f in the weights texture.
                                       // It should always be 255.
-        *size = SkScalarCeilToInt(6*sigma);
+        *size = SkScalarCeilToInt(6*sigma) + 1;
     } else {
         // The Gaussian is bigger than the circle.
         *offset = 0.0f;
@@ -213,6 +213,7 @@ static uint8_t* create_profile(float halfWH, float sigma) {
         weights[i] = eval_at(offset+i, halfWH, halfKernel.get(), kernelWH);
     }
 

[robertphillips, 2016/02/24 12:52:56]

Are we guaranteed that weights[numSteps-1] will always be zero?
Should we just have:
  weights[numSteps-1] = 0;
here?

[dogben, 2016/02/24 15:31:22]

sgtm

+    SkASSERT(weights[numSteps-1] == 0);
     return weights;
 }