[Offline pages] Adding in memory request queue store with tests

components/offline_pages/background/request_queue_in_memory_store.h

Index: components/offline_pages/background/request_queue_in_memory_store.h
diff --git a/components/offline_pages/background/request_queue_in_memory_store.h b/components/offline_pages/background/request_queue_in_memory_store.h
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+++ b/components/offline_pages/background/request_queue_in_memory_store.h
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+// 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.
+
+#ifndef COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_IN_MEMORY_STORE_H_
+#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_IN_MEMORY_STORE_H_
+
+#include <stdint.h>
+
+#include <map>
+
+#include "base/macros.h"
+#include "components/offline_pages/background/request_queue_store.h"
+
+namespace offline_pages {
+
+class SavePageRequest;
+
+// Interface for classes storing save page requests.
+class RequestQueueInMemoryStore : public RequestQueueStore {
+ public:
+  RequestQueueInMemoryStore();
+  ~RequestQueueInMemoryStore() override;
+
+  // RequestQueueStore implementaiton.
+  void GetRequests(const GetRequestsCallback& callback) override;
+  void AddOrUpdateRequest(const SavePageRequest& request,
+                          const UpdateCallback& callback) override;
+  void RemoveRequests(const std::vector<int64_t>& request_ids,
+                      const RemoveCallback& callback) override;
+  void Reset(const ResetCallback& callback) override;
+
+ private:
+  typedef std::map<int64_t, SavePageRequest> RequestsMap;
+  RequestsMap requests_;
+
+  DISALLOW_COPY_AND_ASSIGN(RequestQueueInMemoryStore);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_IN_MEMORY_STORE_H_