[Offline Pages] Introducing StorageManagerClient interface.

components/offline_pages/offline_page_storage_manager.h

 // 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_PAGE_STORAGE_MANAGER_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
-#include "components/offline_pages/offline_page_model.h"
+#include "components/offline_pages/offline_page_types.h"
 
 namespace offline_pages {
 
-// TODO(romax): Keep this as a default value until I find a way to get
-// storage size in C++. (20MB)
-static const int64_t kDefaultStorageSize = 20 * (1 << 20);
-
 class ClientPolicyController;
-struct OfflinePageItem;
 
 // This class is used for storage management of offline pages. It provides
 // a ClearPagesIfNeeded method which is used to clear expired offline pages
 // based on last_access_time and lifetime policy of its namespace.
 // It has its own throttle mechanism so calling the method would not be
 // guaranteed to clear the pages immediately.
 //
 // OfflinePageModel should own and control the lifecycle of this manager.
 // And this manager would use OfflinePageModel to get/remove pages.
 class OfflinePageStorageManager {
  public:
+  // This interface should have no knowledge of offline page model.
+  // This interface should be implemented by clients managed by storage manager.
+  class Client {
+   public:
+    // Asks the client to get all offline pages and invoke |callback|.
+    virtual void GetAllPages(
+        const MultipleOfflinePageItemCallback& callback) = 0;
+
+    // Asks the client to delete pages based on |offline_ids| and invoke
+    // |callback|.
+    virtual void DeletePagesByOfflineId(const std::vector<int64_t>& offline_ids,
+                                        const DeletePageCallback& callback) = 0;
+  };
+
   // Callback used when calling ClearPagesIfNeeded.
   // int: the number of deleted pages.
   // DeletePageResult: result of deleting pages.
-  typedef base::Callback<void(int, OfflinePageModel::DeletePageResult)>
-      ClearPageCallback;
+  typedef base::Callback<void(int, DeletePageResult)> ClearPageCallback;
 
-  explicit OfflinePageStorageManager(OfflinePageModel* model);
+  explicit OfflinePageStorageManager(Client* client,
+                                     ClientPolicyController* policy_controller);
 
   ~OfflinePageStorageManager();
 
   // The manager would *try* to clear pages when called. It may not delete any
   // pages (if clearing condition wasn't satisfied).
   void ClearPagesIfNeeded(const ClearPageCallback& callback);
 
  private:
   // Selects and removes pages that need to be expired. Triggered as a callback
   // to |GetAllPages|.
-  void ClearExpiredPages(
-      const ClearPageCallback& callback,
-      const OfflinePageModel::MultipleOfflinePageItemResult& pages);
+  void ClearExpiredPages(const ClearPageCallback& callback,
+                         const MultipleOfflinePageItemResult& pages);
 
   // Gets offline IDs of all expired pages and return in |offline_ids|.
-  void GetExpiredPageIds(
-      const OfflinePageModel::MultipleOfflinePageItemResult& pages,
-      std::vector<int64_t>& offline_ids);
+  void GetExpiredPageIds(const MultipleOfflinePageItemResult& pages,
+                         std::vector<int64_t>& offline_ids);
 
   // Callback when expired pages has been deleted.
   void OnExpiredPagesDeleted(const ClearPageCallback& callback,
                              int pages_to_clear,
-                             OfflinePageModel::DeletePageResult result);
+                             DeletePageResult result);
 
   // Determine if manager should clear pages.
   bool ShouldClearPages();
 
   // Return true if |page| is expired.
   bool IsPageExpired(const OfflinePageItem& page);
 
   // Not owned.
-  OfflinePageModel* model_;
+  Client* client_;
 
   // Not owned.
   ClientPolicyController* policy_controller_;
 
   bool in_progress_;
 
   base::WeakPtrFactory<OfflinePageStorageManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageStorageManager);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_