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

chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc

Index: chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc
diff --git a/chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc b/chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc
index f069335c56010ed551f99f96963be27c1692e347..5471086376976044fc9b5d4db12cf9e287323644 100644
--- a/chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc
+++ b/chrome/browser/chromeos/policy/device_cloud_policy_store_chromeos.cc
@@ -40,7 +40,8 @@ DeviceCloudPolicyStoreChromeOS::DeviceCloudPolicyStoreChromeOS(
 }
 
 DeviceCloudPolicyStoreChromeOS::~DeviceCloudPolicyStoreChromeOS() {
-  device_settings_service_->RemoveObserver(this);
+  if (device_settings_service_)
+    device_settings_service_->RemoveObserver(this);
 }
 
 void DeviceCloudPolicyStoreChromeOS::Store(
@@ -107,6 +108,7 @@ void DeviceCloudPolicyStoreChromeOS::DeviceSettingsUpdated() {
 }
 
 void DeviceCloudPolicyStoreChromeOS::OnDeviceSettingsServiceShutdown() {
+  device_settings_service_->RemoveObserver(this);
   device_settings_service_ = nullptr;
 }