Switch clipboard_unittests to clipboard_apptests.

BUG=none
R=msw@chromium.org

Review URL: https://codereview.chromium.org/768683003
diff --git a/mojo/BUILD.gn b/mojo/BUILD.gn
index daff64c..525bd5f 100644
--- a/mojo/BUILD.gn
+++ b/mojo/BUILD.gn
@@ -69,7 +69,7 @@
     "//mojo/shell:external_application_unittests",
     "//mojo/shell:mojo_shell_tests",
     "//mojo/tools:message_generator",
-    "//services/clipboard:clipboard_unittests",
+    "//services/clipboard:apptests",
     "//services/js:js_services_unittests",
     "//services/js:js_apptests",
   ]