Separate the NTP app ordering from the app list app ordering

chrome/browser/extensions/app_list_extension_ordering.h

+// Copyright (c) 2013 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_APP_LIST_EXTENSION_ORDERING_H_
+#define CHROME_BROWSER_EXTENSIONS_APP_LIST_EXTENSION_ORDERING_H_
+
+#include <map>
+#include <set>
+
+#include "chrome/browser/extensions/extension_ordering.h"
+#include "sync/api/string_ordinal.h"
+
+// The ordering for apps on the app list. This ordering is represented by a
+// single ordinal
+class AppListExtensionOrdering : public ExtensionOrdering {
+ public:
+  explicit AppListExtensionOrdering(
+      ExtensionScopedPrefs* extension_scoped_prefs);
+  ~AppListExtensionOrdering();
+
+  // ExtensionOrdering implementation.
+  virtual void Initialize(
+      const extensions::ExtensionIdList& extension_ids) OVERRIDE;
+  virtual void FixSyncCollisions() OVERRIDE;
+  virtual void InsertAtFront(const std::string& extension_id) OVERRIDE;
+  virtual void InsertAtBack(const std::string& extension_id) OVERRIDE;
+  virtual void InsertAtNextAvailable(const std::string& extension_id) OVERRIDE;
+  virtual void OnExtensionMoved(
+      const std::string& moved_extension_id,
+      const std::string& predecessor_extension_id,
+      const std::string& successor_extension_id) OVERRIDE;
+  virtual void Erase(const std::string& extension_id) OVERRIDE;
+  virtual bool ExtensionPrecedes(const std::string& extension1,
+                                 const std::string& extension2) OVERRIDE;
+
+  syncer::StringOrdinal GetAppListOrdinal(const std::string& extension_id);
+  // Sets the ordinal for the given |extension_id| as |ordinal|. This causes a
+  // sync.
+  void SetAppListOrdinal(const std::string& extension_id,
+                         const syncer::StringOrdinal& ordinal);
+ private:
+  typedef std::set<std::string> ExtensionIdSet;
+  typedef std::map<syncer::StringOrdinal, ExtensionIdSet,
+      syncer::StringOrdinal::LessThanFn> AppListOrdinalMap;
+
+  void UpdatePrefs(const std::string& extension_id,
+                   const syncer::StringOrdinal& ordinal);
+
+  AppListOrdinalMap app_list_ordinal_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppListExtensionOrdering);
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_APP_LIST_EXTENSION_ORDERING_H_