Finish overriding onMakeColorSpace() for SkImageFilters

Fixes 3 gms in gbr-8888.  Breaks 0 gms in gbr-8888.

Bug: skia:
Change-Id: I3365390b16353821ef6057a7bb68020887e36f72
Reviewed-on: https://skia-review.googlesource.com/13323
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
diff --git a/tests/PDFPrimitivesTest.cpp b/tests/PDFPrimitivesTest.cpp
index de9af07..766bbef 100644
--- a/tests/PDFPrimitivesTest.cpp
+++ b/tests/PDFPrimitivesTest.cpp
@@ -366,6 +366,9 @@
         offset->fX = offset->fY = 0;
         return sk_ref_sp<SkSpecialImage>(source);
     }
+    sk_sp<SkImageFilter> onMakeColorSpace(SkColorSpaceXformer*) const override {
+        return sk_ref_sp(const_cast<DummyImageFilter*>(this));
+    }
 
 private:
     DummyImageFilter(bool visited) : INHERITED(nullptr, 0, nullptr), fVisited(visited) {}