Add a buildflag to use the handle verifier in a per module mode.

base/win/BUILD.gn

Index: base/win/BUILD.gn
diff --git a/base/win/BUILD.gn b/base/win/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..01092735b3ae44276cc9180f26876572772c2a5a
--- /dev/null
+++ b/base/win/BUILD.gn
@@ -0,0 +1,23 @@
+# Copyright (c) 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.
+
+import("//build/buildflag_header.gni")
+
+declare_args() {
+  # Indicates if the handle verifier should operate in a single module mode. By
+  # default a single instance gets shared by all the modules.
+  single_module_mode_handle_verifier = false
+}
+
+# Ensure that the handle verifier is always used in a single module mode for the
+# component builds.
+if (is_component_build) {
+  single_module_mode_handle_verifier = true
+}
+
+buildflag_header("base_win_features") {
+  header = "base_features.h"
+  header_dir = "base/win"
+  flags = [ "SINGLE_MODULE_MODE_HANDLE_VERIFIER=$single_module_mode_handle_verifier" ]
+}