[Sync] Clear LocalDeviceInfoProvider cache on sync DB destruction.

components/browser_sync/browser/profile_sync_service.cc

 // 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.
 
 #include "components/browser_sync/browser/profile_sync_service.h"
 
 #include <stddef.h>
 #include <cstddef>
 #include <map>
 #include <utility>
@@ skipping 789 matching lines @@
     sync_thread_ = doomed_backend->Shutdown(reason);
     doomed_backend.reset();
   }
   base::TimeDelta shutdown_time = base::Time::Now() - shutdown_start_time;
   UMA_HISTOGRAM_TIMES("Sync.Shutdown.BackendDestroyedTime", shutdown_time);
 
   weak_factory_.InvalidateWeakPtrs();
 
   startup_controller_->Reset(GetRegisteredDataTypes());
 
+  // If the sync DB is getting destroyed, the local DeviceInfo is no longer
+  // valid and should be cleared from the cache.
+  if (reason == syncer::ShutdownReason::DISABLE_SYNC) {
+    local_device_->Clear();
+  }
+
   // Clear various flags.
   expect_sync_configuration_aborted_ = false;
   is_auth_in_progress_ = false;
   backend_initialized_ = false;
   cached_passphrase_.clear();
   encryption_pending_ = false;
   encrypt_everything_ = false;
   encrypted_types_ = syncer::SyncEncryptionHandler::SensitiveTypes();
   passphrase_required_reason_ = syncer::REASON_PASSPHRASE_NOT_REQUIRED;
   catch_up_configure_in_progress_ = false;
@@ skipping 1707 matching lines @@
 }
 
 std::string ProfileSyncService::unrecoverable_error_message() const {
   return unrecoverable_error_message_;
 }
 
 tracked_objects::Location ProfileSyncService::unrecoverable_error_location()
     const {
   return unrecoverable_error_location_;
 }