Add base persistence interfaces for Prefetching Offline Pages.

components/offline_pages/core/prefetch/prefetch_item.h

Index: components/offline_pages/core/prefetch/prefetch_item.h
diff --git a/components/offline_pages/core/prefetch/prefetch_item.h b/components/offline_pages/core/prefetch/prefetch_item.h
new file mode 100644
index 0000000000000000000000000000000000000000..48d03a71ae0142d05e0bde8a3ce42a6408fd5c56
--- /dev/null
+++ b/components/offline_pages/core/prefetch/prefetch_item.h
@@ -0,0 +1,95 @@
+// 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_ITEM_H_
+#define COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_ITEM_H_
+
+#include <string>
+
+#include "base/time/time.h"
+#include "components/offline_pages/core/offline_page_item.h"
+#include "components/offline_pages/core/prefetch/prefetch_constants.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+// Data object representing an item progressing through the prefetching process
+// from the moment a URL is requested by a client until its processing id done,
+// successfully or not.
+// Instances of this class are in-memory representations of items in (or to be
+// inserted into) the persistent prefetching data store.
+struct PrefetchItem {
+ public:

[fgorski, 2017/05/10 05:02:53]

nit: struct implies public.

[carlosk, 2017/05/10 22:48:54]

Done.

+  const int64_t INVALID_ID = -1;

[fgorski, 2017/05/10 05:02:53]

will you only allow positive numbers?
If negative are OK, wouldn't 0 be a better invalid_id? (Also tests nicely as
boolean)

[carlosk, 2017/05/10 22:48:53]

As we moved to a string guid this was now removed.

+
+  PrefetchItem() = default;
+  explicit PrefetchItem(const PrefetchItem& other) = default;
+
+  ~PrefetchItem(){};
+
+  bool operator==(const PrefetchItem& other) const;
+
+  // Primary key/ID for this prefetch item.
+  int64_t id = INVALID_ID;
+
+  // The |ClientID| specified by the prefetcher client to be used for the
+  // offline page that might be generated from this item, consolidating a
+  // namespace and a client ID.
+  ClientId client_id;
+
+  // Current prefetching progress state.
+  PrefetchItemState state = PrefetchItemState::NEW_REQ;
+
+  // The URL of the page the client requested to be prefetched.
+  GURL url;
+
+  // The final URL whose page was actually included in a successfully created
+  // archive after redirects, if it was different than the |url|. It will be
+  // left empty if they are the same.
+  GURL final_archived_url;
+
+  // Number of times an attempt was made to generate an archive for this item.
+  int request_archive_attempt_count = 0;
+
+  // Name used to identify the archiving operation being executed by the
+  // prefetching service for processing this item's URL. It is used as the
+  // |operation_name| reported by an incoming GCM message and in the
+  // |GetOperationRequest.name| field of the respective GetOperation RPC.
+  std::string operation_name;
+
+  // The name specific to this item's archive that can be used to build the URL
+  // to allow the downloading of that archive. Will only be set when and if an
+  // archive was successfully created for this item. It will be kept empty
+  // otherwise.
+  std::string archive_body_name;
+
+  // The final size of the generated archive that contains this item's page
+  // snapshot. The archive might also include other articles in a bundle so the
+  // length is not necessarily directly related to this item's page contents.
+  // Will only be set when and if an archive was successfully created for this
+  // item. It holds a negative value otherwise.
+  int64_t archive_body_length = -1;
+
+  // An opaque identifier to the request being served to download this item's
+  // archive.
+  std::string download_id;
+
+  // Time when this item was inserted into the store with the URL to be
+  // prefetched.
+  base::Time creation_time;
+
+  // Time used for the expiration of the item depending on the applicable policy
+  // for its current state. It is initially set with the same value as
+  // |creation_time|. Its value is "refreshed" to the current time on some state
+  // transitions considered significant for the prefetching process.
+  base::Time freshness_time;
+
+  // The reason why a the item was set to the FIN state. Until then its value is

[fgorski, 2017/05/10 05:02:53]

nit: "why a the"?

[carlosk, 2017/05/10 22:48:53]

Done.

+  // meaningless.
+  PrefetchItemErrorCode error_code = PrefetchItemErrorCode::NO_ERROR;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_ITEM_H_