Update .gn to add chrome/chrome_cleaner to gn check

Change-Id: I4442f2e2a9136409831793a396c05150e7607684
Reviewed-on: https://chromium-review.googlesource.com/1136387
Commit-Queue: Chris Sharp <csharp@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575001}

.gn

@@ -88,6 +88,7 @@ check_targets = [
   "//chrome/browser/extensions/*",
   "//chrome/browser/resource_coordinator/*",
   "//chrome/browser/ui/*",
+  "//chrome/chrome_cleaner/*",
   "//chrome/common/*",
   "//chrome/installer/*",
   "//chrome/profiling",