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

components/precache/content/precache_manager.cc

 // Copyright 2013 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.
 
 #include "components/precache/content/precache_manager.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 85 matching lines @@
 
 bool PrecacheManager::IsPrecachingAllowed() const {
   return PrecachingAllowed() == AllowedType::ALLOWED;
 }
 
 PrecacheManager::AllowedType PrecacheManager::PrecachingAllowed() const {
   if (!(sync_service_ && sync_service_->IsEngineInitialized()))
     return AllowedType::PENDING;
 
   // SyncService delegates to SyncPrefs, which must be called on the UI thread.
-  if (history_service_ &&
+  if (history_service_ && !sync_service_->IsLocalSyncEnabled() &&
       sync_service_->GetActiveDataTypes().Has(syncer::SESSIONS) &&
-      !sync_service_->GetEncryptedDataTypes().Has(syncer::SESSIONS))
+      !sync_service_->GetEncryptedDataTypes().Has(syncer::SESSIONS)) {
     return AllowedType::ALLOWED;
+  }
 
   return AllowedType::DISALLOWED;
 }
 
 void PrecacheManager::StartPrecaching(
     const PrecacheCompletionCallback& precache_completion_callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   if (is_precaching_) {
     DLOG(WARNING) << "Cannot start precaching because precaching is already "
@@ skipping 235 matching lines @@
       this));
   precache_fetcher_->Start();
 }
 
 void PrecacheManager::OnHostsReceivedThenDone(
     const history::TopHostsList& host_counts) {
   OnDone();
 }
 
 }  // namespace precache