Separate the NTP app ordering from the app list app ordering

chrome/browser/ui/app_list/app_list_extension_sorting.h

Index: chrome/browser/ui/app_list/app_list_extension_sorting.h
diff --git a/chrome/browser/ui/app_list/app_list_extension_sorting.h b/chrome/browser/ui/app_list/app_list_extension_sorting.h
new file mode 100644
index 0000000000000000000000000000000000000000..209bde8960174d5740f210b1897014d024743afe
--- /dev/null
+++ b/chrome/browser/ui/app_list/app_list_extension_sorting.h
@@ -0,0 +1,108 @@
+// 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_UI_APP_LIST_APP_LIST_EXTENSION_SORTING_H_
+#define CHROME_BROWSER_UI_APP_LIST_APP_LIST_EXTENSION_SORTING_H_
+
+#include <map>
+#include <set>
+#include <string>
+
+#include "chrome/common/extensions/extension.h"
+#include "sync/api/string_ordinal.h"
+
+class ExtensionScopedPrefs;
+class ExtensionServiceInterface;
+class PrefService;
+
+// The order of apps in the app list. This class defines the order by assigning
+// each app a single string ordinal. This class works on an in-memory map of
+// ordinals which it uses to resolve conflicts generated by sync and which it
+// commits to prefs for persistence. The information represented in the in-
+// memory map and prefs should always match once Initialize() is called.
+class AppListExtensionSorting {
+ public:
+  explicit AppListExtensionSorting(
+      ExtensionScopedPrefs* extension_scoped_prefs);
+  ~AppListExtensionSorting();
+  // Set the ExtensionService to syncs order changes.
+  void SetExtensionService(ExtensionServiceInterface* extension_service);
+
+  // Initialize internal data structures that require the |extension_ids| of all
+  // installed extensions. After this is called, the prefs and our internal data
+  // structures should always reflect the same data.
+  void Initialize(const extensions::ExtensionIdList& extension_ids);
+
+  syncer::StringOrdinal GetAppListOrdinalFromPrefs(
+      const std::string& extension_id);
+
+  // Processes extensions sync data by setting the ordinal for the given
+  // |extension_id| as |ordinal|. This can result in ordinal collisions so
+  // FixSyncCollisions() should be called after all extensions are synced.
+  // There should not be an existing ordinal for |extension_id|.
+  void UpdateAppListOrdinalFromSync(const std::string& extension_id,
+                                const syncer::StringOrdinal& ordinal);
+
+  // Resolves any conflicts that might be created as a result result of calls to
+  // SetAppListOrdinalForSync() that results in two extensions having the same
+  // position in the order. After this is called, it is guaranteed that there
+  // will be no collisions.
+  void FixSyncCollisions();
+
+  // Add an extension so that it precedes all other extensions in the order.
+  void InsertAtFront(const std::string& extension_id);
+
+  // Add an extension so that all other extensions precede it in the order.
+  void InsertAtBack(const std::string& extension_id);
+
+  // Updates the moved extension in the order so that it is now located after
+  // the given predecessor and before the successor. Empty strings are used to
+  // indicate no successor or predecessor.
+  void OnExtensionMoved(const std::string& moved_extension_id,
+                        const std::string& predecessor_extension_id,
+                        const std::string& successor_extension_id);
+
+  // Removes an app from the order. Does nothing if |extension_id| is not in
+  // the order.
+  void Erase(const std::string& extension_id);
+
+  // Returns true if |extension1| appears before |extension2| in the order.
+  bool ExtensionPrecedes(const std::string& extension_id1,
+                         const std::string& extension_id2);
+
+  // Returns true if |extension_id| is in the order.
+  bool Contains(const std::string& extension_id);
+
+ private:
+  typedef std::set<std::string> ExtensionIdSet;
+  typedef std::map<syncer::StringOrdinal, ExtensionIdSet,
+      syncer::StringOrdinal::LessThanFn> AppListOrdinalMap;
+
+  // Sets the ordinal for the extension to the ordinal found in prefs. Returns
+  // true if a valid ordinal for the given |extension_id| was found in the
+  // prefs.
+  bool InitializeOrdinalFromPrefs(const std::string& extension_id);
+
+  // Sets the ordinal for any extension in |uninitialized_extensions| which has
+  // a default order defined.
+  void InitializeWithDefaultOrdinals(
+    const std::vector<std::string>& uninitialized_extensions);
+
+  void SetAppListOrdinal(const std::string& extension_id,
+                         const syncer::StringOrdinal& ordinal);
+  void EraseAppListOrdinal(const std::string& extension_id);
+  void UpdatePrefs(const std::string& extension_id,
+                   const syncer::StringOrdinal& ordinal);
+  void UpdatePrefsAndSync(const std::string& extension_id,
+                   const syncer::StringOrdinal& ordinal);
+
+  extensions::ExtensionIdList default_initialized_extensions_;
+  AppListOrdinalMap app_list_ordinal_map_;
+  ExtensionScopedPrefs* extension_scoped_prefs_;  // Weak, owns this instance.
+  ExtensionServiceInterface* extension_service_;  // Weak.
+
+  DISALLOW_COPY_AND_ASSIGN(AppListExtensionSorting);
+};
+
+#endif  // CHROME_BROWSER_UI_APP_LIST_APP_LIST_EXTENSION_SORTING_H_