[Sync] Ensure cryptographer ready before encrypting.

chrome/browser/sync/util/nigori.cc

 // 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.
 
 #include "chrome/browser/sync/util/nigori.h"
 
 #if defined(OS_WIN)
 #include <winsock2.h>  // for htonl
 #else
 #include <arpa/inet.h>
@@ skipping 150 matching lines @@
 std::string GenerateRandomString(size_t size) {
   // TODO(albertb): Use a secure random function.
   std::string random(size, 0);
   for (size_t i = 0; i < size; ++i)
     random[i] = RandInt(0, 0xff);
   return random;
 }
 
 // Enc[Kenc,Kmac](value)
 bool Nigori::Encrypt(const std::string& value, std::string* encrypted) const {
-  DCHECK_LT(0U, value.size());
+  if (0U >= value.size())
+    return false;
 
   std::string iv = GenerateRandomString(kIvSize);
 
   Encryptor encryptor;
   if (!encryptor.Init(encryption_key_.get(), Encryptor::CBC, iv))
     return false;
 
   std::string ciphertext;
   if (!encryptor.Encrypt(value, &ciphertext))
     return false;
@@ skipping 69 matching lines @@
   DCHECK(user_key);
   DCHECK(encryption_key);
   DCHECK(mac_key);
 
   return user_key_->GetRawKey(user_key) &&
       encryption_key_->GetRawKey(encryption_key) &&
       mac_key_->GetRawKey(mac_key);
 }
 
 }  // namespace browser_sync