Create skeleton for the Prefetching store and initial pipeline step.

components/offline_pages/core/client_id.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/client_id.h"
+
+namespace offline_pages {
+
+ClientId::ClientId() {}
+
+ClientId::ClientId(const std::string& name_space, const std::string& id)
+    : name_space(name_space), id(id) {}
+
+bool ClientId::operator==(const ClientId& client_id) const {
+  return name_space == client_id.name_space && id == client_id.id;
+}
+
+bool ClientId::operator<(const ClientId& client_id) const {
+  if (name_space == client_id.name_space)
+    return (id < client_id.id);
+
+  return name_space < client_id.name_space;
+}
+
+}  // namespace offline_pages