[Sync] Clear LocalDeviceInfoProvider cache on sync DB destruction.

components/sync_driver/local_device_info_provider_mock.cc

 // Copyright 2014 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/sync_driver/local_device_info_provider_mock.h"
 
 namespace sync_driver {
 
 LocalDeviceInfoProviderMock::LocalDeviceInfoProviderMock()
   : is_initialized_(false) {}
@@ skipping 12 matching lines @@
           client_name,
           chrome_version,
           sync_user_agent,
           device_type,
           signin_scoped_device_id));
 }
 
 LocalDeviceInfoProviderMock::~LocalDeviceInfoProviderMock() {}
 
 const DeviceInfo* LocalDeviceInfoProviderMock::GetLocalDeviceInfo() const {
-  return is_initialized_ ? local_device_info_.get() : NULL;
+  return is_initialized_ ? local_device_info_.get() : nullptr;
 }
 
 std::string LocalDeviceInfoProviderMock::GetSyncUserAgent() const {
   return "useragent";
 }
 
 std::string LocalDeviceInfoProviderMock::GetLocalSyncCacheGUID() const {
   return local_device_info_.get() ? local_device_info_->guid() : "";
 }
 
 void LocalDeviceInfoProviderMock::Initialize(
     const std::string& cache_guid,
     const std::string& signin_scoped_device_id,
     const scoped_refptr<base::TaskRunner>& blocking_task_runner) {
-  // Ignored for the mock provider.
+  local_device_info_.reset(new DeviceInfo(
+      cache_guid, "client_name", "chrome_version", GetSyncUserAgent(),
+      sync_pb::SyncEnums_DeviceType_TYPE_LINUX, signin_scoped_device_id));
+  SetInitialized(true);
 }
 
 void LocalDeviceInfoProviderMock::Initialize(
     std::unique_ptr<DeviceInfo> local_device_info) {
   local_device_info_.swap(local_device_info);
   SetInitialized(true);
 }
 
 std::unique_ptr<LocalDeviceInfoProvider::Subscription>
 LocalDeviceInfoProviderMock::RegisterOnInitializedCallback(
     const base::Closure& callback) {
   DCHECK(!is_initialized_);
   return callback_list_.Add(callback);
 }
 
+void LocalDeviceInfoProviderMock::Clear() {
+  local_device_info_.reset();
+  is_initialized_ = false;
+}
+
 void LocalDeviceInfoProviderMock::SetInitialized(bool is_initialized) {
   is_initialized_ = is_initialized;
   if (is_initialized_) {
     callback_list_.Notify();
   }
 }
 
 }  // namespace sync_driver