Make SkGpuBlurUtils::GaussianBlur more drawContext centric

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index 37d6c960d7829e15d444bbf4cae70ddab053916c..a2d67d74af7b95344ef5d122decf0bfe22ced499 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -1248,10 +1248,11 @@ bool SkBlurMaskFilterImpl::filterMaskGPU(GrTexture* src,
     // If we're doing a normal blur, we can clobber the pathTexture in the
     // gaussianBlur.  Otherwise, we need to save it for later compositing.
     bool isNormalBlur = (kNormal_SkBlurStyle == fBlurStyle);
-    *result = SkGpuBlurUtils::GaussianBlur(context, src, isNormalBlur && canOverwriteSrc,
-                                           clipRect, nullptr,
-                                           xformedSigma, xformedSigma);
-    if (nullptr == *result) {
+    sk_sp<GrDrawContext> drawContext(SkGpuBlurUtils::GaussianBlur(context, src,
+                                                                  isNormalBlur && canOverwriteSrc,
+                                                                  clipRect, nullptr,
+                                                                  xformedSigma, xformedSigma));
+    if (!drawContext) {
         return false;
     }
 
@@ -1276,15 +1277,10 @@ bool SkBlurMaskFilterImpl::filterMaskGPU(GrTexture* src,
             paint.setCoverageSetOpXPFactory(SkRegion::kReplace_Op);
         }
 
-        sk_sp<GrDrawContext> drawContext(
-                                    context->drawContext(sk_ref_sp((*result)->asRenderTarget())));
-        if (!drawContext) {
-            return false;
-        }
-
         drawContext->drawRect(GrClip::WideOpen(), paint, SkMatrix::I(), clipRect);
     }
 
+    *result = drawContext->asTexture().release();
     return true;
 }