[Sync] Initial support for encrypting any datatype (no UI hookup yet).

chrome/browser/sync/util/cryptographer.h

Index: chrome/browser/sync/util/cryptographer.h
diff --git a/chrome/browser/sync/util/cryptographer.h b/chrome/browser/sync/util/cryptographer.h
index ada084cc07c9a8d44e956e4213570f96130c94c4..adb809b0c1d6936310b6276dcaa0d3b378c2f1f5 100644
--- a/chrome/browser/sync/util/cryptographer.h
+++ b/chrome/browser/sync/util/cryptographer.h
@@ -71,6 +71,10 @@ class Cryptographer {
   bool Decrypt(const sync_pb::EncryptedData& encrypted,
                ::google::protobuf::MessageLite* message) const;
 
+  // Decrypts |encrypted| and returns plaintext decrypted data. If decryption
+  // fails, returns empty string.
+  std::string DecryptToString(const sync_pb::EncryptedData& encrypted) const;
+
   // Encrypts the set of currently known keys into |encrypted|. Returns true if
   // successful.
   bool GetKeys(sync_pb::EncryptedData* encrypted) const;