value_cleanup: fixup ListValue::Append() calls that already have a unique_ptr to use.

tools/clang/value_cleanup/tests/list-value-append-original.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 <memory>
+
 #include "base/values.h"
 
 #define true true
 
+std::unique_ptr<base::Value> ReturnsUniquePtr() {
+  return nullptr;
+}
+
+struct Thing {
+  std::unique_ptr<base::Value> ToValue() { return nullptr; }
+};
+
 void F() {
   base::ListValue list;
   list.Append(new base::FundamentalValue(1 == 0));
   list.Append(new base::FundamentalValue(true));
   list.Append(new base::FundamentalValue(static_cast<unsigned char>(1.0)));
   list.Append(new base::FundamentalValue(double{3}));
   list.Append(new base::StringValue("abc"));
+
+  list.Append(ReturnsUniquePtr().release());
+  Thing thing;
+  list.Append(thing.ToValue().release());
+  std::unique_ptr<base::Value> unique_ptr_var;
+  list.Append(unique_ptr_var.release());
 }