Avoid SYNC_CYCLE_CONTINUATION sync cycles

chrome/browser/sync/test/integration/migration_errors_test.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // TODO(akalin): Rename this file to migration_test.cc.
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/prefs/scoped_user_pref_update.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sync/profile_sync_service_harness.h"
@@ skipping 153 matching lines @@
     // complete.  (Multiple migrations may be handled by each
     // migration cycle, but there's no guarantee of that, so we have
     // to trigger each migration individually.)
     for (MigrationList::const_iterator it = migration_list.begin();
          it != migration_list.end(); ++it) {
       TriggerMigration(*it, trigger_method);
       AwaitMigration(*it);
     }
 
     // Phase 3: Wait for all clients to catch up.
-    ASSERT_TRUE(AwaitQuiescence());
+    //
+    // AwaitQuiescence() will not succeed when notifications are disabled.  We

[akalin, 2012/01/20 22:41:51]

Why is this true?  It seems to me that a single client should be trivially
"quiesced" already.

[rlarocque, 2012/01/20 23:04:56]

Not according to the definition in the integration tests.  It requires that all
clients be "IsFullySynced()", which won't happen automatically when there are no
self-notifications or SYNC_CYCLE_CONTINUATION GetUpdates.

I would like to fix this by relaxing the constraints for AwaitQuiescense(), but
that would break other tests that rely on comparison of timestamps.  In general,
we can't expect timestamps to match unless this clients being compared are both
IsFullySynced().

[akalin, 2012/01/20 23:07:24]

Add TODO to change this back and refer to bug.

+    // can safely avoid calling it because we know that, in the single client
+    // case, there is no one else to wait for.
+    if (!do_test_without_notifications) {
+      AwaitQuiescence();
+    }
 
     // Re-enable notifications if we disabled it.
     if (do_test_without_notifications) {
       EnableNotifications();
     }
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MigrationTest);
 };
@@ skipping 263 matching lines @@
 
   // Phase 5: Verify that preferences can still be synchronized.
   VerifyPrefSync();
 
   // Phase 6: Verify that sessions are registered and enabled.
   ASSERT_TRUE(GetClient(0)->IsTypeRunning(syncable::SESSIONS));
   ASSERT_TRUE(GetClient(0)->IsTypePreferred(syncable::SESSIONS));
 }
 
 }  // namespace