mandoline filesystem: add a sqlite3 vfs to proxy filesystem usage.

sql/correct_sql_test_base.h

+// Copyright 2015 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.
+
+#ifndef SQL_CORRECT_SQL_TEST_BASE_H_
+#define SQL_CORRECT_SQL_TEST_BASE_H_
+
+// This header exists to get around gn check. We want to use the same testing
+// code in both the sql_unittests target (which uses gtest and targets the
+// filesystem directly) and sql_apptests.mojo (which uses mojo:apptest and
+// proxies the additional filesystem access to mojo:filesystem). Both of these
+// files define a class named sql::SQLTestBase and have the same interface.
+//
+// Unfortunately, gn check does not understand preprocessor directives. If it
+// did, the following code would be gn check clean, but since it isn't, we
+// stuff this redirection header in its own file, give it its own source_set
+// target, and then set check_includes to false.
+//
+// This work around was suggested by brettw@.
+#if defined(MOJO_APPTEST_IMPL)
+#include "sql/mojo/sql_test_base.h"
+#else
+#include "sql/test/sql_test_base.h"
+#endif
+
+#endif  // SQL_CORRECT_SQL_TEST_BASE_H_
+