Added Aura notification that relaunch and powerwash is required in case of downgrade.

chromeos/dbus/update_engine_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_UPDATE_ENGINE_CLIENT_H_
 #define CHROMEOS_DBUS_UPDATE_ENGINE_CLIENT_H_
 
+#include <string>
+#include <vector>
+
 #include "base/callback.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 <string>
-
 namespace chromeos {
 
 // UpdateEngineClient is used to communicate with the update engine.
 class CHROMEOS_EXPORT UpdateEngineClient : public DBusClient {
  public:
+  static const std::string kReleaseChannelDev;
+  static const std::string kReleaseChannelBeta;
+  static const std::string kReleaseChannelStable;
+
+  static const std::vector<std::string> kReleaseChannelsList;

[stevenjb, 2014/10/01 22:26:44]

No complex static members:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Static_and_Gl...

I don't think we should expose this publicly anyway, we should create helper
methods as part of this class instead.

[ygorshenin1, 2014/10/02 14:21:35]

Done.

+
   // Edges for state machine
   //    IDLE->CHECKING_FOR_UPDATE
   //    CHECKING_FOR_UPDATE->IDLE
   //    CHECKING_FOR_UPDATE->UPDATE_AVAILABLE
   //    ...
   //    FINALIZING->UPDATE_NEED_REBOOT
   // Any state can transition to REPORTING_ERROR_EVENT and then on to IDLE.
   enum UpdateStatusOperation {
     UPDATE_STATUS_ERROR = -1,
     UPDATE_STATUS_IDLE = 0,
@@ skipping 107 matching lines @@
   // Create() should be used instead.
   UpdateEngineClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(UpdateEngineClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_UPDATE_ENGINE_CLIENT_H_