Add a UniqueVector class to GN

tools/gn/unique_vector_unittest.cc

Index: tools/gn/unique_vector_unittest.cc
diff --git a/tools/gn/unique_vector_unittest.cc b/tools/gn/unique_vector_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0f5d461b04d38f32dbe3b3c35be5918e4f17bc89
--- /dev/null
+++ b/tools/gn/unique_vector_unittest.cc
@@ -0,0 +1,43 @@
+// Copyright (c) 2013 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 <algorithm>
+
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "tools/gn/unique_vector.h"
+
+TEST(UniqueVector, PushBack) {
+  UniqueVector<int> foo;
+  EXPECT_TRUE(foo.push_back(1));
+  EXPECT_FALSE(foo.push_back(1));
+  EXPECT_TRUE(foo.push_back(2));
+  EXPECT_TRUE(foo.push_back(0));
+  EXPECT_FALSE(foo.push_back(2));
+  EXPECT_FALSE(foo.push_back(1));
+
+  EXPECT_EQ(3u, foo.size());
+  EXPECT_EQ(1, foo[0]);
+  EXPECT_EQ(2, foo[1]);
+  EXPECT_EQ(0, foo[2]);
+
+  // Verify those results with IndexOf as well.
+  EXPECT_EQ(0u, foo.IndexOf(1));
+  EXPECT_EQ(1u, foo.IndexOf(2));
+  EXPECT_EQ(2u, foo.IndexOf(0));
+  EXPECT_EQ(static_cast<size_t>(-1), foo.IndexOf(99));
+}
+
+TEST(UniqueVector, PushBackViaSwap) {
+  UniqueVector<std::string> vect;
+  std::string a("a");
+  EXPECT_TRUE(vect.PushBackViaSwap(&a));
+  EXPECT_EQ("", a);
+
+  a = "a";
+  EXPECT_FALSE(vect.PushBackViaSwap(&a));
+  EXPECT_EQ("a", a);
+
+  EXPECT_EQ(0u, vect.IndexOf("a"));
+}