Fix for crash on large image blur sigma values.

src/effects/SkGpuBlurUtils.cpp

Index: src/effects/SkGpuBlurUtils.cpp
diff --git a/src/effects/SkGpuBlurUtils.cpp b/src/effects/SkGpuBlurUtils.cpp
index 6133db11d20e41bdf31a06d5d7379c4f44a3e348..9da08e6f71f0f32d84d21aef5d027e4ffa7bdcb4 100644
--- a/src/effects/SkGpuBlurUtils.cpp
+++ b/src/effects/SkGpuBlurUtils.cpp
@@ -28,11 +28,15 @@ static void scale_rect(SkRect* rect, float xScale, float yScale) {
     rect->fBottom = SkScalarMul(rect->fBottom, yScale);
 }
 
-static float adjust_sigma(float sigma, int *scaleFactor, int *radius) {
+static float adjust_sigma(float sigma, int maxTextureSize, int *scaleFactor, int *radius) {
     *scaleFactor = 1;
     while (sigma > MAX_BLUR_SIGMA) {
         *scaleFactor *= 2;
         sigma *= 0.5f;
+        if (*scaleFactor > maxTextureSize) {
+            *scaleFactor = maxTextureSize;
+            sigma = MAX_BLUR_SIGMA;
+        }
     }
     *radius = static_cast<int>(ceilf(sigma * 3.0f));
     SkASSERT(*radius <= GrConvolutionEffect::kMaxKernelRadius);
@@ -129,8 +133,9 @@ GrTexture* GaussianBlur(GrContext* context,
     SkIRect clearRect;
     int scaleFactorX, radiusX;
     int scaleFactorY, radiusY;
-    sigmaX = adjust_sigma(sigmaX, &scaleFactorX, &radiusX);
-    sigmaY = adjust_sigma(sigmaY, &scaleFactorY, &radiusY);
+    int maxTextureSize = context->getMaxTextureSize();
+    sigmaX = adjust_sigma(sigmaX, maxTextureSize, &scaleFactorX, &radiusX);
+    sigmaY = adjust_sigma(sigmaY, maxTextureSize, &scaleFactorY, &radiusY);
 
     SkRect srcRect(rect);
     scale_rect(&srcRect, 1.0f / scaleFactorX, 1.0f / scaleFactorY);