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

components/offline_pages/background/request_queue_store.h

Index: components/offline_pages/background/request_queue_store.h
diff --git a/components/offline_pages/background/request_queue_store.h b/components/offline_pages/background/request_queue_store.h
new file mode 100644
index 0000000000000000000000000000000000000000..24f2fd7526fedeacdf83bd04bfcdb0c2780505c3
--- /dev/null
+++ b/components/offline_pages/background/request_queue_store.h
@@ -0,0 +1,46 @@
+// 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_STORE_H_
+#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_STORE_H_
+
+#include <stdint.h>
+#include <vector>
+
+#include "base/callback.h"
+
+namespace offline_pages {
+
+class SavePageRequest;
+
+// Interface for classes storing save page requests.
+class RequestQueueStore {
+ public:
+  typedef base::Callback<void(bool, const std::vector<SavePageRequest>&)>
+      GetRequestsCallback;
+  typedef base::Callback<void(bool)> UpdateCallback;
+  typedef base::Callback<void(bool)> ResetCallback;
+
+  virtual ~RequestQueueStore(){};
+
+  // Gets all of the requests from the store.
+  virtual void GetRequests(const GetRequestsCallback& callback) = 0;

[Pete Williamson, 2016/05/03 20:38:52]

Why make this async again?  (Sorry if I already asked that and forgot the
answer.)  It seems that having this async will make the scheduling much harder
and less efficient.

[fgorski, 2016/05/03 21:50:21]

You know we need to read these from the drive either way, right?

[Pete Williamson, 2016/05/03 22:00:25]

Ah yes, that was why.  This is OK as is.

+
+  // Asynchronously adds or updates request in store.
+  // Result of the update is passed in the callback.
+  virtual void AddOrUpdateRequest(const SavePageRequest& request,
+                                  const UpdateCallback& callback) = 0;
+
+  // Asynchronously removes requests from the store using their IDs.
+  // Result of the update is passed in the callback.

[Pete Williamson, 2016/05/03 20:38:52]

Let's be a bit more specific - returns true if anything gets deleted.

[fgorski, 2016/05/03 21:50:21]

Done.

+  virtual void RemoveRequests(const std::vector<int64_t>& request_ids,
+                              const UpdateCallback& callback) = 0;
+
+  // Resets the store.
+  virtual void Reset(const ResetCallback& callback) = 0;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_STORE_H_