[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 d8a4711946e001db2ad1e4a285aaf94039a391c3..619ab3d23e82e9e82fa1e7e7112108dd05f92e35 100644
--- a/extensions/renderer/api_bindings_system.h
+++ b/extensions/renderer/api_bindings_system.h
@@ -83,6 +83,9 @@ 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_; }
   APITypeReferenceMap* type_reference_map() { return &type_reference_map_; }