Implement pref_value_map swap function.

chrome/browser/prefs/pref_value_map_unittest.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 "base/values.h"
 #include "chrome/browser/prefs/pref_value_map.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 class PrefValueMapTest : public testing::Test {
 };
@@ skipping 69 matching lines @@
   EXPECT_TRUE(check.SetValue("d", Value::CreateStringValue("test")));
 
   reference.GetDifferingKeys(&check, &differing_paths);
   expected_differing_paths.clear();
   expected_differing_paths.push_back("a");
   expected_differing_paths.push_back("b");
   expected_differing_paths.push_back("d");
   expected_differing_paths.push_back("e");
   EXPECT_EQ(expected_differing_paths, differing_paths);
 }
+
+TEST_F(PrefValueMapTest, SwapTwoMaps) {
+  PrefValueMap first_map;
+  EXPECT_TRUE(first_map.SetValue("a", Value::CreateStringValue("test")));
+  EXPECT_TRUE(first_map.SetValue("b", Value::CreateStringValue("test")));
+  EXPECT_TRUE(first_map.SetValue("c", Value::CreateStringValue("test")));
+
+  PrefValueMap second_map;
+  EXPECT_TRUE(second_map.SetValue("d", Value::CreateStringValue("test")));
+  EXPECT_TRUE(second_map.SetValue("e", Value::CreateStringValue("test")));
+  EXPECT_TRUE(second_map.SetValue("f", Value::CreateStringValue("test")));
+
+  first_map.Swap(&second_map);
+
+  EXPECT_TRUE(first_map.GetValue("d", NULL));
+  EXPECT_TRUE(first_map.GetValue("e", NULL));
+  EXPECT_TRUE(first_map.GetValue("f", NULL));
+
+  EXPECT_TRUE(second_map.GetValue("a", NULL));
+  EXPECT_TRUE(second_map.GetValue("b", NULL));
+  EXPECT_TRUE(second_map.GetValue("c", NULL));
+}