Abandon user sign in when policy is retrieved before session started

chromeos/dbus/session_manager_client.h

 // 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.
 
 #ifndef CHROMEOS_DBUS_SESSION_MANAGER_CLIENT_H_
 #define CHROMEOS_DBUS_SESSION_MANAGER_CLIENT_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/dbus_client.h"
 #include "chromeos/dbus/dbus_client_implementation_type.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "third_party/cros_system_api/dbus/login_manager/dbus-constants.h"
 
 namespace cryptohome {
 class Identification;
 }
 
 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:
     virtual ~Observer() {}
 
     // Called when the owner key is set.
     virtual void OwnerKeySet(bool success) {}
 
     // Called when the property change is complete.
     virtual void PropertyChangeComplete(bool success) {}
@@ skipping 95 matching lines @@
   // Enumerates active user sessions. Usually Chrome naturally keeps track of
   // active users when they are added into current session. When Chrome is
   // restarted after crash by session_manager it only receives cryptohome id and
   // user_id_hash for one user. This method is used to retrieve list of all
   // active users.
   virtual void RetrieveActiveSessions(
       const ActiveSessionsCallback& callback) = 0;
 
   // 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.
   virtual void RetrieveDevicePolicy(const RetrievePolicyCallback& callback) = 0;
 
   // Same as RetrieveDevicePolicy() but blocks until a reply is received, and
   // returns the policy synchronously. Returns an empty string if the method
   // call fails.
   // This may only be called in situations where blocking the UI thread is
   // considered acceptable (e.g. restarting the browser after a crash or after
@@ skipping 154 matching lines @@
   // Create() should be used instead.
   SessionManagerClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SessionManagerClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_SESSION_MANAGER_CLIENT_H_