[Sync] Allow sync start without sign-in if the local sync backend is on.

components/sync/engine_impl/sync_scheduler_impl.h

Index: components/sync/engine_impl/sync_scheduler_impl.h
diff --git a/components/sync/engine_impl/sync_scheduler_impl.h b/components/sync/engine_impl/sync_scheduler_impl.h
index 6a6208ae674b7b6929a97eb88406c50779f89874..c9fe0bd633b76c074b3439418bfedf432144aa85 100644
--- a/components/sync/engine_impl/sync_scheduler_impl.h
+++ b/components/sync/engine_impl/sync_scheduler_impl.h
@@ -40,7 +40,8 @@ class SyncSchedulerImpl : public SyncScheduler, public base::NonThreadSafe {
   SyncSchedulerImpl(const std::string& name,
                     BackoffDelayProvider* delay_provider,
                     SyncCycleContext* context,
-                    Syncer* syncer);
+                    Syncer* syncer,
+                    bool ignore_auth_credentials);
 
   // Calls Stop().
   ~SyncSchedulerImpl() override;
@@ -291,6 +292,9 @@ class SyncSchedulerImpl : public SyncScheduler, public base::NonThreadSafe {
   // One-shot timer for scheduling GU retry according to delay set by server.
   base::OneShotTimer retry_timer_;
 
+  // Dictates if the scheduler should wait for authentication to happen or not.
+  bool ignore_auth_credentials_;
+
   base::WeakPtrFactory<SyncSchedulerImpl> weak_ptr_factory_;
 
   // A second factory specially for weak_handle_this_, to allow the handle