Add an LRUBoundedCache class.

base/lru_bounded_cache_unittest.cc

+// Copyright 2016 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/lru_bounded_cache.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+TEST(LRUBoundedCacheTest, Basic) {
+  LRUBoundedCache<int> cache(3);
+
+  EXPECT_FALSE(cache.Insert(1));
+  EXPECT_EQ(1UL, cache.Size());
+
+  EXPECT_TRUE(cache.Insert(1));
+  EXPECT_EQ(1UL, cache.Size());
+
+  EXPECT_FALSE(cache.Insert(2));
+  EXPECT_EQ(2UL, cache.Size());
+
+  EXPECT_FALSE(cache.Insert(3));
+  EXPECT_EQ(3UL, cache.Size());
+
+  EXPECT_TRUE(cache.Insert(3));
+  EXPECT_EQ(3UL, cache.Size());
+
+  EXPECT_FALSE(cache.Insert(4));
+  EXPECT_EQ(3UL, cache.Size());
+
+  EXPECT_FALSE(cache.Insert(1));
+  EXPECT_EQ(3UL, cache.Size());
+}
+
+}  // namespace base