[Sync] Removing duplicate includes, part 2.

components/sync/base/nigori_unittest.cc

 // 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.
 
 #include "components/sync/base/nigori.h"
 
-#include <string>
-
 #include "base/strings/string_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace syncer {
 namespace {
 
 TEST(SyncNigoriTest, Permute) {
   Nigori nigori;
   EXPECT_TRUE(nigori.InitByDerivation("example.com", "username", "password"));
 
@@ skipping 130 matching lines @@
   EXPECT_EQ(original, plaintext);
 
   std::string permuted1, permuted2;
   EXPECT_TRUE(nigori1.Permute(Nigori::Password, original, &permuted1));
   EXPECT_TRUE(nigori2.Permute(Nigori::Password, original, &permuted2));
   EXPECT_EQ(permuted1, permuted2);
 }
 
 }  // anonymous namespace
 }  // namespace syncer