chromeos: Wait for service to be available when getting system salt

chromeos/cryptohome/system_salt_getter.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_CRYPTOHOME_SYSTEM_SALT_GETTER_H_
 #define CHROMEOS_CRYPTOHOME_SYSTEM_SALT_GETTER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
+#include "base/memory/weak_ptr.h"
 #include "chromeos/chromeos_export.h"
 
 namespace chromeos {
 
 // This class is used to get the system salt from cryptohome and cache it.
 class CHROMEOS_EXPORT SystemSaltGetter {
  public:
   typedef base::Callback<void(const std::string& system_salt)>
       GetSystemSaltCallback;
 
@@ skipping 19 matching lines @@
   // Returns system hash in hex encoded ascii format, cached by a prior call
   // to GetSystemSalt(). Note: this may return an empty string (e.g. if
   // GetSystemSalt() is not yet called).
   std::string GetCachedSystemSalt();
 
  protected:
   SystemSaltGetter();
   ~SystemSaltGetter();
 
  private:
+  // Used to implement GetSystemSalt().
+  void GetSystemSaltInternal(const GetSystemSaltCallback& callback,
+                             bool service_is_available);
+
   // Loads the system salt from cryptohome and caches it.
   void LoadSystemSalt();
 
   std::string system_salt_;
 
+  base::WeakPtrFactory<SystemSaltGetter> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(SystemSaltGetter);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_CRYPTOHOME_SYSTEM_SALT_GETTER_H_