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..ee17c113bc355454b7689c30698631dd3e7c727b
--- /dev/null
+++ b/base/win/BUILD.gn
@@ -0,0 +1,21 @@
+# 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
+}
+
+if (is_component_build) {
+  single_module_mode_handle_verifier = true

[Nico, 2016/06/07 16:48:18]

this means that if you explicitly set single_module_mode_handle_verifier to
false but do a component build, you end up with it true, yes? is that what you
want?

[Sébastien Marchand, 2016/06/07 17:47:58]

Yes, I'll add a comment.

+}
+
+buildflag_header("base_win_features") {
+  header = "base_features.h"
+  header_dir = "base/win"
+  flags = [ "SINGLE_MODULE_MODE_HANDLE_VERIFIER=single_module_mode_handle_verifier" ]
+}