Implement Windows GPO support for "dlpref" in component updater.

components/update_client/utils_unittest.cc

+// 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 "components/update_client/utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+using std::string;
+
+namespace update_client {
+
+TEST(BuildProtocolRequest, DownloadPreference) {
+  const string emptystr;
+
+  // Verifies that an empty |download_preference| is not serialized.
+  const string request_no_dlpref = BuildProtocolRequest(
+      emptystr, emptystr, emptystr, emptystr, emptystr, emptystr, emptystr);
+  EXPECT_EQ(string::npos, request_no_dlpref.find(" dlpref="));
+
+  // Verifies that |download_preference| is serialized.
+  const string request_with_dlpref = BuildProtocolRequest(
+      emptystr, emptystr, emptystr, emptystr, "some pref", emptystr, emptystr);
+  EXPECT_NE(string::npos, request_with_dlpref.find(" dlpref=\"some pref\""));
+}
+
+}  // namespace update_client