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

chromeos/dbus/update_engine_client.h

Index: chromeos/dbus/update_engine_client.h
diff --git a/chromeos/dbus/update_engine_client.h b/chromeos/dbus/update_engine_client.h
index eddd9125cb0463a1cd334f40a5a6d49e88f491e8..1b06c8446aa90f71e273b5c5742a06c7f8408522 100644
--- a/chromeos/dbus/update_engine_client.h
+++ b/chromeos/dbus/update_engine_client.h
@@ -5,19 +5,26 @@
 #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