Add an experimental permissions API for extensions.

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 6e25c5b9228282b71e42ee371abefd3c3699c667..529c94ad4a12e34cae53c5a37951389e60e00101 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -187,6 +187,16 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   void AddGrantedPermissions(const std::string& extension_id,
                              const ExtensionPermissionSet* permissions);
 
+  // Gets the active permission set for the specified extension. This may
+  // differ from the permissions in the manifest due to the optional
+  // permissions API.
+  ExtensionPermissionSet* GetActivePermissions(
+      const std::string& extension_id);
+
+  // Sets the active |permissions| for the extension with |extension_id|.
+  void SetActivePermissions(const std::string& extension_id,
+                            const ExtensionPermissionSet* permissions);
+
   // Returns true if the user enabled this extension to be loaded in incognito
   // mode.
   bool IsIncognitoEnabled(const std::string& extension_id);