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..d0520b9d176d192317dc08f9c177f224f3b58063
--- /dev/null
+++ b/chrome/common/safe_browsing/file_type_policies_test_util.cc
@@ -0,0 +1,36 @@
+// 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()
+    : orig_config_(new DownloadFileTypeConfig()) {
+  // Make a copy of the global config so we can put it back later.
+  // Swap out, copy, swap back in.
+  SwapConfig(orig_config_);
+  std::unique_ptr<DownloadFileTypeConfig> copy_config = DuplicateConfig();
+  SwapConfig(copy_config);
+}
+
+FileTypePoliciesTestOverlay::~FileTypePoliciesTestOverlay() {
+  SwapConfig(orig_config_);
+}
+
+void FileTypePoliciesTestOverlay::SwapConfig(
+    std::unique_ptr<DownloadFileTypeConfig>& new_config) const {
+  FileTypePolicies::GetInstance()->SwapConfig(new_config);
+}
+
+std::unique_ptr<DownloadFileTypeConfig>
+FileTypePoliciesTestOverlay::DuplicateConfig() const {
+  std::unique_ptr<DownloadFileTypeConfig> new_config(
+      new DownloadFileTypeConfig());
+  // Deep copy
+  new_config->CopyFrom(*orig_config_);
+  return new_config;
+}
+
+}  // namespace safe_browsing