Abandon user sign in when policy is retrieved before session started

chromeos/dbus/blocking_method_caller.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_BLOCKING_METHOD_CALLER_H_
 #define CHROMEOS_DBUS_BLOCKING_METHOD_CALLER_H_
 
 #include "base/macros.h"
 #include "base/synchronization/waitable_event.h"
 #include "chromeos/chromeos_export.h"
 #include "dbus/message.h"
 
 namespace dbus {
 
 class Bus;
 class ObjectProxy;
+class ScopedDBusError;
 
 }  // namespace dbus
 
 namespace chromeos {
 
 // A utility class to call D-Bus methods in a synchronous (blocking) way.
 // Note: Blocking the thread until it returns is not a good idea in most cases.
 //       Avoid using this class as hard as you can.
 class CHROMEOS_EXPORT BlockingMethodCaller {
  public:
   BlockingMethodCaller(dbus::Bus* bus, dbus::ObjectProxy* proxy);
   virtual ~BlockingMethodCaller();
 
   // Calls the method and blocks until it returns.
   std::unique_ptr<dbus::Response> CallMethodAndBlock(
       dbus::MethodCall* method_call);
 
+  // Calls the method and blocks until it returns. Populates the |error| and
+  // returns null in case of an error.
+  std::unique_ptr<dbus::Response> CallMethodAndBlockWithError(
+      dbus::MethodCall* method_call,
+      dbus::ScopedDBusError* error_out);
+
  private:
   dbus::Bus* bus_;
   dbus::ObjectProxy* proxy_;
   base::WaitableEvent on_blocking_method_call_;
 
   DISALLOW_COPY_AND_ASSIGN(BlockingMethodCaller);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_BLOCKING_METHOD_CALLER_H_