Abandon user sign in when policy is retrieved before session started

chromeos/dbus/session_manager_client.h

Index: chromeos/dbus/session_manager_client.h
diff --git a/chromeos/dbus/session_manager_client.h b/chromeos/dbus/session_manager_client.h
index b294b761c8b9c692d7414f78e8432d46d663ec21..e015f7f5a69d1b6a951b017bdc119953621e4bc3 100644
--- a/chromeos/dbus/session_manager_client.h
+++ b/chromeos/dbus/session_manager_client.h
@@ -27,6 +27,18 @@ namespace chromeos {
 // SessionManagerClient is used to communicate with the session manager.
 class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
  public:
+  // The result type received from session manager on request to retrieve the
+  // policy.

[emaxx, 2017/04/18 15:03:17]

Please explain in the comment the restriction that are put on this enum due to
it being used for UMA, e.g.:
// This enum is used to define the buckets for an enumerated UMA histogram.
// Hence,
//   (a) existing enumerated constants should never be deleted or reordered, and
//   (b) new constants should only be appended at the end of the enumeration.

[igorcov, 2017/04/20 14:52:29]

Done.

+  enum RetrievePolicyResponseType {
+    SUCCESS,                             // The policy retrieved successfully.
+    SESSION_DOES_NOT_EXIST,              // Retrieve policy request issued
+                                         // before session started.
+    OTHER_ERROR,                         // Other type of error while retrieving
+                                         // policy.
+    RETRIEVE_POLICY_RESPONSE_TYPE_COUNT  // Has to be the last value of
+                                         // enumeration. Used for UMA.
+  };
+
   // Interface for observing changes from the session manager.
   class Observer {
    public:
@@ -142,10 +154,12 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
 
   // Used for RetrieveDevicePolicy, RetrievePolicyForUser and
   // RetrieveDeviceLocalAccountPolicy. Takes a serialized protocol buffer as
-  // string.  Upon success, we will pass a protobuf to the callback.  On
-  // failure, we will pass "".
+  // string.  Upon success, we will pass a protobuf and SUCCESS |response_type|
+  // to the callback. On failure, we will pass "" and the details of error type
+  // in |response_type|.
   using RetrievePolicyCallback =
-      base::Callback<void(const std::string& protobuf)>;
+      base::Callback<void(const std::string& protobuf,
+                          const RetrievePolicyResponseType& response_type)>;
 
   // Fetches the device policy blob stored by the session manager.  Upon
   // completion of the retrieve attempt, we will call the provided callback.