Move ownership of AppSorting from ExtensionPrefs to ExtensionSystem

extensions/shell/browser/shell_extensions_browser_client.cc

Index: extensions/shell/browser/shell_extensions_browser_client.cc
diff --git a/extensions/shell/browser/shell_extensions_browser_client.cc b/extensions/shell/browser/shell_extensions_browser_client.cc
index 623980f40a5db00cbd854df1fccbb78e3f6bd12b..0489b798dcd4f71ba3c4ee0aef5b22258f0d88e5 100644
--- a/extensions/shell/browser/shell_extensions_browser_client.cc
+++ b/extensions/shell/browser/shell_extensions_browser_client.cc
@@ -156,11 +156,6 @@ bool ShellExtensionsBrowserClient::DidVersionUpdate(BrowserContext* context) {
 void ShellExtensionsBrowserClient::PermitExternalProtocolHandler() {
 }
 
-scoped_ptr<AppSorting> ShellExtensionsBrowserClient::CreateAppSorting(
-    content::BrowserContext* context) {
-  return scoped_ptr<AppSorting>(new NullAppSorting);
-}
-
 bool ShellExtensionsBrowserClient::IsRunningInForcedAppMode() {
   return false;
 }