[Sync] Persist keystore key across restarts

chrome/browser/sync/sync_prefs.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 CHROME_BROWSER_SYNC_SYNC_PREFS_H_
 #define CHROME_BROWSER_SYNC_SYNC_PREFS_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 76 matching lines @@
   // Changes are still made to the prefs even if
   // HasKeepEverythingSynced() is true, but won't be visible until
   // SetKeepEverythingSynced(false) is called.
   void SetPreferredDataTypes(
     syncer::ModelTypeSet registered_types,
     syncer::ModelTypeSet preferred_types);
 
   // This pref is set outside of sync.
   bool IsManaged() const;
 
-  // Use this encryption bootstrap token once already syncing.
+  // Use this encryption bootstrap token if we're using an explicit passphrase.
   std::string GetEncryptionBootstrapToken() const;
   void SetEncryptionBootstrapToken(const std::string& token);
 
+  // Use this keystore bootstrap token if we're not using an explicit
+  // passphrase.
+  std::string GetKeystoreEncryptionBootstrapToken() const;
+  void SetKeystoreEncryptionBootstrapToken(const std::string& token);
+
   // Maps |data_type| to its corresponding preference name.
   static const char* GetPrefNameForDataType(syncer::ModelType data_type);
 
 #if defined(OS_CHROMEOS)
   // Use this spare bootstrap token only when setting up sync for the first
   // time.
   std::string GetSpareBootstrapToken() const;
   void SetSpareBootstrapToken(const std::string& token);
 #endif
 
@@ skipping 43 matching lines @@
   // etc.
   typedef std::map<syncer::ModelType, syncer::ModelTypeSet> PrefGroupsMap;
   PrefGroupsMap pref_groups_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncPrefs);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SYNC_PREFS_H_