Switch SkBlurImageFilter over to new onFilterImage interface

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 374a561030254561941ecf21e67d4a65cdfffe80..f7662c6e75fe5353bdafbcc1466ac93cebab0803 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -593,7 +593,16 @@ SkSpecialImage* SkImageFilter::filterInput(int index,
         return SkRef(src);
     }
 
-    return input->filterImage(src, this->mapContext(ctx), offset);
+    SkAutoTUnref<SkSpecialImage> result(input->filterImage(src, this->mapContext(ctx), offset));
+
+    if (src->peekTexture() && !result->peekTexture()) {
+        // Keep the result on the GPU - this is still required for some
+        // image filters that don't support GPU in all cases
+        GrContext* context = src->peekTexture()->getContext();
+        result.reset(result->makeTextureImage(src->internal_getProxy(), context));
+    }
+
+    return result.release();
 }
 
 #if SK_SUPPORT_GPU