Refactor QUICHE platform flag utilities.

Move flag count macro implementations from http2, quic, and spdy platform
directories to quiche/common/platform, removing some code duplication, and
making all macros available from all three components.

Feature flag accessors, protocol flags, and flag saver are not touched
by this CL.

PiperOrigin-RevId: 348632606
Change-Id: I623bc0ff532020188cce51e802118cb622f1d101
diff --git a/common/platform/api/quiche_flag_utils.h b/common/platform/api/quiche_flag_utils.h
new file mode 100644
index 0000000..0534064
--- /dev/null
+++ b/common/platform/api/quiche_flag_utils.h
@@ -0,0 +1,19 @@
+// Copyright 2020 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 QUICHE_COMMON_PLATFORM_API_QUICHE_FLAG_UTILS_H_
+#define QUICHE_COMMON_PLATFORM_API_QUICHE_FLAG_UTILS_H_
+
+#include "net/quiche/common/platform/impl/quiche_flag_utils_impl.h"
+
+#define QUICHE_RELOADABLE_FLAG_COUNT QUICHE_RELOADABLE_FLAG_COUNT_IMPL
+#define QUICHE_RELOADABLE_FLAG_COUNT_N QUICHE_RELOADABLE_FLAG_COUNT_N_IMPL
+
+#define QUICHE_RESTART_FLAG_COUNT QUICHE_RESTART_FLAG_COUNT_IMPL
+#define QUICHE_RESTART_FLAG_COUNT_N QUICHE_RESTART_FLAG_COUNT_N_IMPL
+
+#define QUICHE_CODE_COUNT QUICHE_CODE_COUNT_IMPL
+#define QUICHE_CODE_COUNT_N QUICHE_CODE_COUNT_N_IMPL
+
+#endif  // QUICHE_COMMON_PLATFORM_API_QUICHE_FLAG_UTILS_H_