Convert app_launch_index and page_index from int to StringOrdinal.

chrome/browser/extensions/extension_prefs.h

Index: chrome/browser/extensions/extension_prefs.h
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index e791e8c840af8127f7c13339092c689513430ec6..9b94ab55944ae1fbf15e237321cb7cd87c37bbf1 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -106,11 +106,12 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   void SetToolbarOrder(const std::vector<std::string>& extension_ids);
 
   // Called when an extension is installed, so that prefs get created.
-  // If |page_index| is -1, and the then a page will be found for the App.
+  // If |page_index| is kUnsetIndex, and the then a page will be found
+  //  for the App.
   void OnExtensionInstalled(const Extension* extension,
                             Extension::State initial_state,
                             bool from_webstore,
-                            int page_index);
+                            std::string page_index);
 
   // Called when an extension is uninstalled, so that prefs get cleaned up.
   void OnExtensionUninstalled(const std::string& extension_id,
@@ -273,30 +274,32 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   // Get the application launch index for an extension with |extension_id|. This
   // determines the order of which the applications appear on the New Tab Page.
   // A value of 0 generally indicates top left. If the extension has no launch
-  // index a -1 value is returned.
-  int GetAppLaunchIndex(const std::string& extension_id);
+  // index a kUnsetIndex value is returned.
+  std::string GetAppLaunchIndex(const std::string& extension_id);
 
   // Sets a specific launch index for an extension with |extension_id|.
-  void SetAppLaunchIndex(const std::string& extension_id, int index);
+  void SetAppLaunchIndex(const std::string& extension_id,
+                         const std::string& index);
 
   // Gets the next available application launch index. This is 1 higher than the
   // highest current application launch index found for the page |on_page|.
-  int GetNextAppLaunchIndex(int on_page);
+  std::string GetNextAppLaunchIndex(std::string on_page);
 
   // Gets the page a new app should install to. Starts on page 0, and if there
   // are N or more apps on it, tries to install on the next page.
-  int GetNaturalAppPageIndex();
+  std::string GetNaturalAppPageIndex();
 
   // Sets the order the apps should be displayed in the app launcher.
   void SetAppLauncherOrder(const std::vector<std::string>& extension_ids);
 
   // Get the application page index for an extension with |extension_id|.  This
   // determines which page an app will appear on in page-based NTPs.  If
-  // the app has no page specified, -1 is returned.
-  int GetPageIndex(const std::string& extension_id);
+  // the app has no page specified, kUnsetIndex is returned.
+  std::string GetPageIndex(const std::string& extension_id);
 
   // Sets a specific page index for an extension with |extension_id|.
-  void SetPageIndex(const std::string& extension_id, int index);
+  void SetPageIndex(const std::string& extension_id,
+                    const std::string& index);
 
   // Returns true if the user repositioned the app on the app launcher via drag
   // and drop.
@@ -420,6 +423,11 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
                              const std::string& pref_key,
                              const base::ListValue** out_value);
 
+  // Reads a string pref |pref_key| from extension with id |extension_id|
+  bool ReadExtensionPrefString(const std::string& extension_id,
+                               const std::string& pref_key,
+                               std::string* out_value);
+
   // Interprets the list pref, |pref_key| in |extension_id|'s preferences, as a
   // URLPatternSet. The |valid_schemes| specify how to parse the URLPatterns.
   bool ReadExtensionPrefURLPatternSet(const std::string& extension_id,
@@ -477,6 +485,9 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   // Migrates the permissions data in the pref store.
   void MigratePermissions(const ExtensionIdSet& extension_ids);
 
+  // Migrates the app launcher and page index values.
+  void MigrateAppIndex(const ExtensionIdSet& extension_ids);
+
   // Checks whether there is a state pref for the extension and if so, whether
   // it matches |check_state|.
   bool DoesExtensionHaveState(const std::string& id,