sk_tool::Registry: make an iterator.

Change-Id: Icf4e31b50bbd91b7ea330a1300f736d6dfd0a41c
Reviewed-on: https://skia-review.googlesource.com/144500
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Auto-Submit: Hal Canary <halcanary@google.com>
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 2a0925e..5667f41 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -88,7 +88,7 @@
 
 namespace DM {
 
-GMSrc::GMSrc(skiagm::GMRegistry::Factory factory) : fFactory(factory) {}
+GMSrc::GMSrc(skiagm::GMFactory factory) : fFactory(factory) {}
 
 Error GMSrc::draw(SkCanvas* canvas) const {
     std::unique_ptr<skiagm::GM> gm(fFactory(nullptr));