Improve DeviceSettingsService documentation

chrome/browser/chromeos/settings/device_settings_service.h

Index: chrome/browser/chromeos/settings/device_settings_service.h
diff --git a/chrome/browser/chromeos/settings/device_settings_service.h b/chrome/browser/chromeos/settings/device_settings_service.h
index e0806584f8d147a26e221a6346b147078b143cfe..ea97e1aa4e30520cb15f7460812a61ef98529f77 100644
--- a/chrome/browser/chromeos/settings/device_settings_service.h
+++ b/chrome/browser/chromeos/settings/device_settings_service.h
@@ -111,7 +111,7 @@ class DeviceSettingsService : public SessionManagerClient::Observer {
   // the InstallAttributes class.
   void SetDeviceMode(policy::DeviceMode device_mode);
 
-  const enterprise_management::PolicyData* policy_data() {
+  const enterprise_management::PolicyData* policy_data() const {
     return policy_data_.get();
   }
 
@@ -125,8 +125,12 @@ class DeviceSettingsService : public SessionManagerClient::Observer {
   // Returns the currently used owner key.
   scoped_refptr<ownership::PublicKey> GetPublicKey();
 
-  // Returns the status generated by the last operation.
-  Status status() { return store_status_; }
+  // Returns the status generated by the *last operation*.

[emaxx, 2017/06/01 20:13:31]

nit: What about also renaming this method so that this peculiarity becomes
obvious? E.g. last_operation_status.

[Thiemo Nagel, 2017/06/02 11:25:39]

I might do that in a follow-up CL.  Ideally, the observers should pass the
status so that the status() method can be removed completely.  I haven't looked
through the code enough to understand whether that would be feasible, though.

+  // WARNING: It is not correct to take this method as an indication of whether
+  // DeviceSettingsService contains valid device settings. In order to answer
+  // that question, simply check whether device_settings() is different from
+  // nullptr.
+  Status status() const { return store_status_; }
 
   // Triggers an attempt to pull the public half of the owner key from disk and
   // load the device settings.