[Offline pages] Extracting and templatizing types for store callbacks

components/offline_pages/offline_store_types.h

Index: components/offline_pages/offline_store_types.h
diff --git a/components/offline_pages/offline_store_types.h b/components/offline_pages/offline_store_types.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_OFFLINE_STORE_TYPES_H_
+#define COMPONENTS_OFFLINE_PAGES_OFFLINE_STORE_TYPES_H_
+
+#include <stdint.h>
+
+#include <set>
+#include <utility>
+#include <vector>
+
+// This file contains common types and callbacks used by storage of various
+// offline page related components.
+namespace offline_pages {
+
+// TODO(fgorski): This enum is meant to replace |LoadStatus|.
+// Current store state. When LOADED, the store is operational. When
+// loading or reset fails, it is reflected appropriately.
+enum class StoreState {
+  NOT_LOADED,      // Store is not loaded yet.
+  LOADED,          // Store is properly loaded and operational.
+  FAILED_LOADING,  // Store initialization failed.
+  FAILED_RESET,    // Resetting the store failed.
+};
+
+// Statuses referring to actions taken on items in the stores.
+enum class ItemActionStatus {
+  SUCCESS,
+  ALREADY_EXISTS,
+  NOT_FOUND,
+  STORE_ERROR,
+};
+
+// Collective result for store update.
+template <typename T>
+class StoreUpdateResult {
+ public:
+  explicit StoreUpdateResult(StoreState state)
+      : store_state(state) {}
+  ~StoreUpdateResult() {}
+
+  // List of Offline ID to item action status mappings.
+  // It is meant to be consumed by the original caller of the operation.
+  std::vector<std::pair<int64_t, ItemActionStatus>> item_statuses;
+
+  // List of successfully updated offline page items as seen after operation
+  // concludes. It is meant to be used when passing to the observers.
+  std::vector<T> updated_items;
+
+  // State of the store after the operation is done.
+  StoreState store_state;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_STORE_TYPES_H_