Reland of Use base::flat_map for base::Value dictionary storage.

base/values_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 "base/values.h"
 
 #include <stddef.h>
 
 #include <limits>
 #include <memory>
@@ skipping 1503 matching lines @@
   EXPECT_FALSE(main_list.GetList(2, NULL));
   EXPECT_FALSE(main_list.GetList(3, NULL));
   EXPECT_FALSE(main_list.GetList(4, NULL));
   EXPECT_FALSE(main_list.GetList(5, NULL));
   EXPECT_TRUE(main_list.GetList(6, NULL));
   EXPECT_FALSE(main_list.GetList(7, NULL));
 }
 
 TEST(ValuesTest, SelfSwap) {
   base::Value test(1);
-  using namespace std;
-  swap(test, test);
+  std::swap(test, test);
   EXPECT_TRUE(test.GetInt() == 1);
 }
 
 }  // namespace base