Attempt to recover sync token for managed user once we detected that sync auth fails.

chrome/browser/chromeos/login/supervised_user_manager.h

Index: chrome/browser/chromeos/login/supervised_user_manager.h
diff --git a/chrome/browser/chromeos/login/supervised_user_manager.h b/chrome/browser/chromeos/login/supervised_user_manager.h
index b0ad266e1a671f6316e1c29ad33bd60afd403650..06b5e702c82c1f8e17590c2577bee66af3257666 100644
--- a/chrome/browser/chromeos/login/supervised_user_manager.h
+++ b/chrome/browser/chromeos/login/supervised_user_manager.h
@@ -8,8 +8,10 @@
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/strings/string16.h"
 #include "base/values.h"
+#include "chrome/browser/profiles/profile.h"
 
 class PrefRegistrySimple;
 
@@ -30,6 +32,9 @@ extern const int kMinPasswordRevision;
 // lookup methods that make sense only for supervised users.
 class SupervisedUserManager {
  public:
+  typedef base::Callback<void(const std::string& /* token */)>
+      LoadTokenCallback;
+
   // Registers user manager preferences.
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
@@ -104,6 +109,14 @@ class SupervisedUserManager {
       const std::string& user_id,
       const base::DictionaryValue* password_info) = 0;
 
+  // Loads a sync oauth token in background, and passes it to callback.
+  virtual void LoadSupervisedUserToken(Profile* profile,
+                                       const LoadTokenCallback& callback) = 0;
+
+  // Configures sync service with oauth token.
+  virtual void ConfigureSyncWithToken(Profile* profile,
+                                      const std::string& token) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(SupervisedUserManager);
 };