[Offline Pages] Set up the initial prefetching service.

components/offline_pages/core/prefetch/prefetch_service_impl_unittest.cc

+// Copyright 2017 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/offline_pages/core/prefetch/prefetch_service_impl.h"
+
+#include "components/offline_pages/core/client_namespace_constants.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+TEST(PrefetchServiceTest, ServiceDoesNotCrash) {
+  PrefetchServiceImpl service;
+
+  service.AddCandidatePrefetchURLs(std::vector<PrefetchService::PrefetchURL>());
+  service.RemoveAllUnprocessedPrefetchURLs(kSuggestedArticlesNamespace);
+  service.RemovePrefetchURLsByClientId({kSuggestedArticlesNamespace, "123"});
+}
+
+}  // namespace offline_pages