Add sampling of unknown filetypes in download protection.

chrome/common/safe_browsing/file_type_policies_test_util.cc

Index: chrome/common/safe_browsing/file_type_policies_test_util.cc
diff --git a/chrome/common/safe_browsing/file_type_policies_test_util.cc b/chrome/common/safe_browsing/file_type_policies_test_util.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5c9b5f9c34557348e893aa57f1f52da0eec15a67
--- /dev/null
+++ b/chrome/common/safe_browsing/file_type_policies_test_util.cc
@@ -0,0 +1,19 @@
+// 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 "chrome/common/safe_browsing/file_type_policies_test_util.h"
+
+namespace safe_browsing {
+
+FileTypePoliciesTestOverlay::FileTypePoliciesTestOverlay()
+    : policies_(new FileTypePolicies()) {
+  policies_->PopulateFromResourceBundle();
+  FileTypePolicies::SetInstanceForTests(policies_.get());
+}
+
+FileTypePoliciesTestOverlay::~FileTypePoliciesTestOverlay() {
+  FileTypePolicies::SetInstanceForTests(nullptr);
+}
+
+}  // namespace safe_browsing