Create skeleton for the Prefetching store and initial pipeline step.

components/offline_pages/core/prefetch/prefetch_service_impl.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 <utility>
 
-#include "base/memory/ptr_util.h"
 #include "components/offline_pages/core/prefetch/prefetch_dispatcher_impl.h"
 
 namespace offline_pages {
 
-PrefetchServiceImpl::PrefetchServiceImpl()
-    : dispatcher_(base::MakeUnique<PrefetchDispatcherImpl>()) {}
+PrefetchServiceImpl::PrefetchServiceImpl(
+    std::unique_ptr<PrefetchStore> store,
+    std::unique_ptr<PrefetchDispatcher> dispatcher)
+    : store_(std::move(store)), dispatcher_(std::move(dispatcher)) {
+  dispatcher_->SetService(this);
+}
 
 PrefetchServiceImpl::~PrefetchServiceImpl() = default;
 
 PrefetchDispatcher* PrefetchServiceImpl::GetDispatcher() {
   return dispatcher_.get();
 };
 
+PrefetchStore* PrefetchServiceImpl::GetStore() {
+  return store_.get();
+};
+
 void PrefetchServiceImpl::Shutdown() {}
 
 }  // namespace offline_pages