Refactor the various ways to control what users can do to extensions.

chrome/browser/ui/webui/extensions/extension_settings_handler.h

Index: chrome/browser/ui/webui/extensions/extension_settings_handler.h
===================================================================
--- chrome/browser/ui/webui/extensions/extension_settings_handler.h	(revision 140193)
+++ chrome/browser/ui/webui/extensions/extension_settings_handler.h	(working copy)
@@ -37,6 +37,7 @@
 
 namespace extensions {
 class Extension;
+class ManagementPolicy;
 }
 
 // Information about a page running in an extension, for example a popup bubble,
@@ -173,6 +174,9 @@
   // Note: This may be NULL in unit tests.
   ExtensionService* extension_service_;
 
+  // A convenience member, filled once the extension_service_ is known.
+  extensions::ManagementPolicy* management_policy_;
+
   // Used to pick the directory when loading an extension.
   scoped_refptr<SelectFileDialog> load_extension_dialog_;