ChromeOS: Per-user time zone: refactor tests first.

chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.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 "chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 22 matching lines @@
     scoped_refptr<base::SequencedTaskRunner> background_task_runner)
     : device_settings_service_(device_settings_service),
       install_attributes_(install_attributes),
       background_task_runner_(background_task_runner),
       weak_factory_(this) {
   device_settings_service_->AddObserver(this);
   device_settings_service_->SetDeviceMode(install_attributes_->GetMode());
 }
 
 DeviceCloudPolicyStoreChromeOS::~DeviceCloudPolicyStoreChromeOS() {
-  device_settings_service_->RemoveObserver(this);
+  if (device_settings_service_)
+    device_settings_service_->RemoveObserver(this);
 }
 
 void DeviceCloudPolicyStoreChromeOS::Store(
     const em::PolicyFetchResponse& policy) {
   // The policy and the public key must have already been loaded by the device
   // settings service.
   DCHECK(is_initialized());
 
   // Cancel all pending requests.
   weak_factory_.InvalidateWeakPtrs();
@@ skipping 46 matching lines @@
       base::Bind(&DeviceCloudPolicyStoreChromeOS::OnPolicyToStoreValidated,
                  weak_factory_.GetWeakPtr()));
 }
 
 void DeviceCloudPolicyStoreChromeOS::DeviceSettingsUpdated() {
   if (!weak_factory_.HasWeakPtrs())
     UpdateFromService();
 }
 
 void DeviceCloudPolicyStoreChromeOS::OnDeviceSettingsServiceShutdown() {
+  device_settings_service_->RemoveObserver(this);
   device_settings_service_ = nullptr;
 }
 
 std::unique_ptr<DeviceCloudPolicyValidator>
 DeviceCloudPolicyStoreChromeOS::CreateValidator(
     const em::PolicyFetchResponse& policy) {
   std::unique_ptr<DeviceCloudPolicyValidator> validator(
       DeviceCloudPolicyValidator::Create(
           base::MakeUnique<em::PolicyFetchResponse>(policy),
           background_task_runner_));
@@ skipping 117 matching lines @@
     UMA_HISTOGRAM_BOOLEAN(kDMTokenCheckHistogram, true);
   } else {
     LOG(ERROR) << "Device policy read on enrolled device yields "
                << "no DM token! Status: " << service_status << ".";
     chromeos::StartupUtils::MarkEnrollmentRecoveryRequired();
     UMA_HISTOGRAM_BOOLEAN(kDMTokenCheckHistogram, false);
   }
 }
 
 }  // namespace policy