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

chrome/browser/sync/util/cryptographer.cc

Index: chrome/browser/sync/util/cryptographer.cc
diff --git a/chrome/browser/sync/util/cryptographer.cc b/chrome/browser/sync/util/cryptographer.cc
index 747b09469995af7be418d12751a0f2d35c156dab..9b166efebd43c43c6bb30671aa0794a10e440ee8 100644
--- a/chrome/browser/sync/util/cryptographer.cc
+++ b/chrome/browser/sync/util/cryptographer.cc
@@ -59,19 +59,24 @@ bool Cryptographer::Encrypt(const ::google::protobuf::MessageLite& message,
 bool Cryptographer::Decrypt(const sync_pb::EncryptedData& encrypted,
                             ::google::protobuf::MessageLite* message) const {
   DCHECK(message);
+  std::string plaintext = DecryptToString(encrypted);
+  return message->ParseFromString(plaintext);
+}
 
+std::string Cryptographer::DecryptToString(
+    const sync_pb::EncryptedData& encrypted) const {
   NigoriMap::const_iterator it = nigoris_.find(encrypted.key_name());
   if (nigoris_.end() == it) {
     NOTREACHED() << "Cannot decrypt message";
-    return false;  // Caller should have called CanDecrypt(encrypt).
+    return std::string("");  // Caller should have called CanDecrypt(encrypt).
   }
 
   std::string plaintext;
   if (!it->second->Decrypt(encrypted.blob(), &plaintext)) {
-    return false;
+    return std::string("");
   }
 
-  return message->ParseFromString(plaintext);
+  return plaintext;
 }
 
 bool Cryptographer::GetKeys(sync_pb::EncryptedData* encrypted) const {