Add a Restore() method to ValueStore and make StorageAPI use it

chrome/browser/extensions/api/storage/settings_backend.h

 // Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_BACKEND_H_
 #define CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_BACKEND_H_
 
-#include <map>
-#include <set>
 #include <string>
 
-#include "base/compiler_specific.h"
 #include "base/files/file_path.h"
-#include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "chrome/browser/extensions/api/storage/settings_observer.h"
-#include "chrome/browser/extensions/api/storage/settings_storage_factory.h"
 #include "chrome/browser/extensions/api/storage/settings_storage_quota_enforcer.h"
-#include "sync/api/syncable_service.h"
 
 namespace syncer {
-class SyncErrorFactory;
+class SyncableService;
 }
 
+class ValueStore;
+
 namespace extensions {
+class SettingsStorageFactory;
 
-class SettingsSyncProcessor;
-class SyncableSettingsStorage;
-
-// Manages ValueStore objects for extensions, including routing
-// changes from sync to them.
-// Lives entirely on the FILE thread.
-class SettingsBackend : public syncer::SyncableService {
+class SettingsBackend {
  public:
-  // |storage_factory| is use to create leveldb storage areas.
-  // |base_path| is the base of the extension settings directory, so the
-  // databases will be at base_path/extension_id.
-  // |observers| is the list of observers to settings changes.
-  SettingsBackend(
-      const scoped_refptr<SettingsStorageFactory>& storage_factory,
-      const base::FilePath& base_path,
-      syncer::ModelType sync_type,
-      const syncer::SyncableService::StartSyncFlare& flare,
-      const SettingsStorageQuotaEnforcer::Limits& quota,
-      const scoped_refptr<SettingsObserverList>& observers);
-
+  SettingsBackend(const scoped_refptr<SettingsStorageFactory>& storage_factory,
+                  const base::FilePath& base_path,
+                  const SettingsStorageQuotaEnforcer::Limits& quota);
   virtual ~SettingsBackend();
 
   // Gets a weak reference to the storage area for |extension_id|.
   // Must be run on the FILE thread.
-  ValueStore* GetStorage(const std::string& extension_id) const;
+  virtual ValueStore* GetStorage(const std::string& extension_id) = 0;
 
   // Deletes all setting data for an extension. Call on the FILE thread.
-  void DeleteStorage(const std::string& extension_id);
+  virtual void DeleteStorage(const std::string& extension_id) = 0;
 
-  // syncer::SyncableService implementation.
-  virtual syncer::SyncDataList GetAllSyncData(
-      syncer::ModelType type) const OVERRIDE;
-  virtual syncer::SyncMergeResult MergeDataAndStartSyncing(
-      syncer::ModelType type,
-      const syncer::SyncDataList& initial_sync_data,
-      scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
-      scoped_ptr<syncer::SyncErrorFactory> sync_error_factory) OVERRIDE;
-  virtual syncer::SyncError ProcessSyncChanges(
-      const tracked_objects::Location& from_here,
-      const syncer::SyncChangeList& change_list) OVERRIDE;
-  virtual void StopSyncing(syncer::ModelType type) OVERRIDE;
+  // A slight hack so we can get a SyncableService from a SettingsBackend if
+  // it's actually a SyncStorageBackend. If called on a LocalStorageBackend,
+  // this asserts and returns null.
+  virtual syncer::SyncableService* GetAsSyncableService();
+
+  SettingsStorageFactory* storage_factory() const {
+    return storage_factory_.get();
+  }
+  const base::FilePath& base_path() const { return base_path_; }
+  const SettingsStorageQuotaEnforcer::Limits& quota() const { return quota_; }
+
+ protected:
+  // Creates a ValueStore decorated with quota-enforcing behavior (the default
+  // for both sync and local stores). If the database is corrupt,
+  // SettingsStorageQuotaEnforcer will try and restore it as part of the
+  // initialization process (by necessity, since we need to read the database to
+  // calculate the storage).
+  scoped_ptr<SettingsStorageQuotaEnforcer> CreateStorageForExtension(
+      const std::string& extension_id) const;
 
  private:
-  // Gets a weak reference to the storage area for a given extension,
-  // initializing sync with some initial data if sync enabled.
-  SyncableSettingsStorage* GetOrCreateStorageWithSyncData(
-      const std::string& extension_id,
-      const base::DictionaryValue& sync_data) const;
-
-  // Gets all extension IDs known to extension settings.  This may not be all
-  // installed extensions.
-  std::set<std::string> GetKnownExtensionIDs() const;
-
-  // Creates a new SettingsSyncProcessor for an extension.
-  scoped_ptr<SettingsSyncProcessor> CreateSettingsSyncProcessor(
-      const std::string& extension_id) const;
-
-  // The Factory to use for creating leveldb storage areas.
+  // The Factory to use for creating new ValueStores.
   const scoped_refptr<SettingsStorageFactory> storage_factory_;
 
-  // The base file path to create any leveldb databases at.
+  // The base file path to use when creating new ValueStores.
   const base::FilePath base_path_;
 
   // Quota limits (see SettingsStorageQuotaEnforcer).
   const SettingsStorageQuotaEnforcer::Limits quota_;
 
-  // The list of observers to settings changes.
-  const scoped_refptr<SettingsObserverList> observers_;
-
-  // A cache of ValueStore objects that have already been created.
-  // Ensure that there is only ever one created per extension.
-  typedef std::map<std::string, linked_ptr<SyncableSettingsStorage> >
-      StorageObjMap;
-  mutable StorageObjMap storage_objs_;
-
-  // Current sync model type. Either EXTENSION_SETTINGS or APP_SETTINGS.
-  syncer::ModelType sync_type_;
-
-  // Current sync processor, if any.
-  scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
-
-  // Current sync error handler if any.
-  scoped_ptr<syncer::SyncErrorFactory> sync_error_factory_;
-
-  syncer::SyncableService::StartSyncFlare flare_;
-
   DISALLOW_COPY_AND_ASSIGN(SettingsBackend);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_STORAGE_SETTINGS_BACKEND_H_