autoupdate_EndToEnd: Fix a syntax error.

BUG=b:24158510
TEST=Test does not fail with SyntaxError on moblab

Change-Id: I9f96d79988ac3d4c251b828c678beae52ee74e89
Reviewed-on: https://chromium-review.googlesource.com/304407
Commit-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Dan Shi <dshi@chromium.org>
diff --git a/server/site_tests/autoupdate_EndToEndTest/autoupdate_EndToEndTest.py b/server/site_tests/autoupdate_EndToEndTest/autoupdate_EndToEndTest.py
index 5f414a6..1bcc395 100755
--- a/server/site_tests/autoupdate_EndToEndTest/autoupdate_EndToEndTest.py
+++ b/server/site_tests/autoupdate_EndToEndTest/autoupdate_EndToEndTest.py
@@ -1434,7 +1434,7 @@
                     'notification (%s). This could be an updater %s; check the '
                     '%s. For a detailed log of update events, check the %s.' %
                     (action, EVENT_TYPE_DICT[expected['event_type']],
-                     EVENT_TYPE_DICT[actual['event_type']], problem
+                     EVENT_TYPE_DICT[actual['event_type']], problem,
                      self._WHERE_UPDATE_LOG, self._WHERE_OMAHA_LOG))
         if 'version' in mismatched_attrs:
             return ('The updater reported an unexpected version despite '