remove imagefilter::sizeconstraint

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1571033002

Review URL: https://codereview.chromium.org/1571033002
diff --git a/src/effects/SkGpuBlurUtils.cpp b/src/effects/SkGpuBlurUtils.cpp
index 13b6b0a..77a8501 100644
--- a/src/effects/SkGpuBlurUtils.cpp
+++ b/src/effects/SkGpuBlurUtils.cpp
@@ -167,8 +167,7 @@
                         const SkRect& dstBounds,
                         const SkRect* srcBounds,
                         float sigmaX,
-                        float sigmaY,
-                        GrTextureProvider::SizeConstraint constraint) {
+                        float sigmaY) {
     SkASSERT(context);
     SkIRect clearRect;
     int scaleFactorX, radiusX;
@@ -211,12 +210,12 @@
     GrTexture* tempTexture;
     SkAutoTUnref<GrTexture> temp1, temp2;
 
-    temp1.reset(context->textureProvider()->createTexture(desc, constraint));
+    temp1.reset(context->textureProvider()->createApproxTexture(desc));
     dstTexture = temp1.get();
     if (canClobberSrc) {
         tempTexture = srcTexture;
     } else {
-        temp2.reset(context->textureProvider()->createTexture(desc, constraint));
+        temp2.reset(context->textureProvider()->createApproxTexture(desc));
         tempTexture = temp2.get();
     }