sync: reland scheduler ownership refactoring, now with less crash

sync/engine/sync_scheduler_impl.h

 // Copyright (c) 2012 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.
 
 #ifndef SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_
 #define SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_
 
 #include <map>
 #include <string>
 
@@ skipping 93 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
                            SaveConfigurationWhileThrottled);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
                            SaveNudgeWhileThrottled);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
                            ContinueCanaryJobConfig);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerWhiteboxTest,
       ContinueNudgeWhileExponentialBackOff);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerTest, TransientPollFailure);
   FRIEND_TEST_ALL_PREFIXES(SyncSchedulerTest, GetInitialBackoffDelay);
+  FRIEND_TEST_ALL_PREFIXES(SyncSchedulerTest,
+                           ServerConnectionChangeDuringBackoff);
 
   struct WaitInterval {
     enum Mode {
       // Uninitialized state, should not be set in practice.
       UNKNOWN = -1,
       // A wait interval whose duration has been affected by exponential
       // backoff.
       // EXPONENTIAL_BACKOFF intervals are nudge-rate limited to 1 per interval.
       EXPONENTIAL_BACKOFF,
       // A server-initiated throttled interval.  We do not allow any syncing
@@ skipping 200 matching lines @@
   // take place during a sync cycle. We call this out because such violations
   // could result in tight sync loops hitting sync servers.
   bool no_scheduling_allowed_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncSchedulerImpl);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_