[Extensions Bindings] Notify of event unregistration on invalidation

extensions/renderer/api_bindings_system.h

Index: extensions/renderer/api_bindings_system.h
diff --git a/extensions/renderer/api_bindings_system.h b/extensions/renderer/api_bindings_system.h
index 2af86014169189f480f4f825583670f7714bf34d..157fa76a783897b74c0391fc733d8dddc0bca8b1 100644
--- a/extensions/renderer/api_bindings_system.h
+++ b/extensions/renderer/api_bindings_system.h
@@ -84,6 +84,9 @@ class APIBindingsSystem {
   void RegisterCustomType(const std::string& type_name,
                           const CustomTypeHandler& function);
 
+  // Handles any cleanup necessary before releasing the given |context|.
+  void WillReleaseContext(v8::Local<v8::Context> context);
+
   APIRequestHandler* request_handler() { return &request_handler_; }
   APIEventHandler* event_handler() { return &event_handler_; }
   APITypeReferenceMap* type_reference_map() { return &type_reference_map_; }