Create skeleton for the Prefetching store and initial pipeline step.

components/offline_pages/core/prefetch/prefetch_store.h

Index: components/offline_pages/core/prefetch/prefetch_store.h
diff --git a/components/offline_pages/core/prefetch/prefetch_store.h b/components/offline_pages/core/prefetch/prefetch_store.h
new file mode 100644
index 0000000000000000000000000000000000000000..4f084d5e442d01b95fa49e9f05af8a716bcfc3b3
--- /dev/null
+++ b/components/offline_pages/core/prefetch/prefetch_store.h
@@ -0,0 +1,18 @@
+// 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.
+
+#ifndef COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_STORE_H_
+#define COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_STORE_H_
+
+namespace offline_pages {
+
+// Persistent storage access class for prefetching offline pages data.
+class PrefetchStore {
+ public:
+  virtual ~PrefetchStore() = default;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_STORE_H_