Convert //tools to use std::unique_ptr

tools/gn/value_unittest.cc

 // Copyright 2014 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 <stdint.h>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/test_with_scope.h"
 #include "tools/gn/value.h"
 
@@ skipping 16 matching lines @@
   listval.list_value().push_back(Value(nullptr, false));
   listval.list_value().push_back(Value(nullptr, static_cast<int64_t>(42)));
   // Printing lists always causes embedded strings to be quoted (ignoring the
   // quote flag), or else they wouldn't make much sense.
   EXPECT_EQ("[\"hi\\\"me\", true, false, 42]", listval.ToString(false));
   EXPECT_EQ("[\"hi\\\"me\", true, false, 42]", listval.ToString(true));
 
   // Scopes.
   TestWithScope setup;
   Scope* scope = new Scope(setup.scope());
-  Value scopeval(nullptr, scoped_ptr<Scope>(scope));
+  Value scopeval(nullptr, std::unique_ptr<Scope>(scope));
   EXPECT_EQ("{ }", scopeval.ToString(false));
 
   scope->SetValue("a", Value(nullptr, static_cast<int64_t>(42)), nullptr);
   scope->SetValue("b", Value(nullptr, "hello, world"), nullptr);
   EXPECT_EQ("{\n  a = 42\n  b = \"hello, world\"\n}", scopeval.ToString(false));
 }