Check node references during sync DB init

chrome/browser/sync/syncable/syncable_id.h

 // Copyright (c) 2011 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_SYNCABLE_SYNCABLE_ID_H_
 #define CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_ID_H_
 #pragma once
 
 #include <iosfwd>
 #include <limits>
@@ skipping 69 matching lines @@
   }
   inline bool operator != (const Id& that) const {
     return s_ != that.s_;
   }
   inline bool operator < (const Id& that) const {
     return s_ < that.s_;
   }
   inline bool operator > (const Id& that) const {
     return s_ > that.s_;
   }
+
+  const std::string& value() const {
+    return s_;
+  }
+
   // Return the next highest ID in the lexicographic ordering.  This is
   // useful for computing upper bounds on std::sets that are ordered
   // by operator<.
   Id GetLexicographicSuccessor() const;
 
   // Note: |lowercase_query| should be passed in as lower case.
   bool ContainsStringCaseInsensitive(const std::string& lowercase_query) const;
 
   // Dumps the ID as a value and returns it.  Transfers ownership of
   // the StringValue to the caller.
@@ skipping 21 matching lines @@
   friend class SyncableIdTest;
 
   std::string s_;
 };
 
 Id GetNullId();
 
 }  // namespace syncable
 
 #endif  // CHROME_BROWSER_SYNC_SYNCABLE_SYNCABLE_ID_H_