[Sync] Enable UserEvents by default.

ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory_unittest.cc

Index: ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory_unittest.cc
diff --git a/ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory_unittest.cc b/ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory_unittest.cc
index f4bcf9819c003f7c9a624b785d3a4df81745ca18..739159428b09f4c0f8b77b3f0e1d1bdbe9d539e2 100644
--- a/ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory_unittest.cc
+++ b/ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory_unittest.cc
@@ -48,6 +48,7 @@ class IOSChromeProfileSyncServiceFactoryTest : public testing::Test {
     datatypes.push_back(syncer::SESSIONS);
     datatypes.push_back(syncer::PROXY_TABS);
     datatypes.push_back(syncer::TYPED_URLS);
+    datatypes.push_back(syncer::USER_EVENTS);
 
     return datatypes;
   }