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/gm/imagefiltersbase.cpp b/gm/imagefiltersbase.cpp
index 8c702b2..f088f67 100644
--- a/gm/imagefiltersbase.cpp
+++ b/gm/imagefiltersbase.cpp
@@ -41,6 +41,9 @@
                                         SkIPoint* offset) const override {
         return nullptr;
     }
+    sk_sp<SkImageFilter> onMakeColorSpace(SkColorSpaceXformer*) const override {
+        return nullptr;
+    }
 
 private:
     typedef SkImageFilter INHERITED;
@@ -83,6 +86,9 @@
         offset->set(0, 0);
         return sk_ref_sp<SkSpecialImage>(source);
     }
+    sk_sp<SkImageFilter> onMakeColorSpace(SkColorSpaceXformer*) const override {
+        return sk_ref_sp(const_cast<IdentityImageFilter*>(this));
+    }
 
 private:
     IdentityImageFilter(sk_sp<SkImageFilter> input) : INHERITED(&input, 1, nullptr) {}