Move the event attach/detach logic on unload from event.js to

extensions/renderer/v8_schema_registry.cc

Index: extensions/renderer/v8_schema_registry.cc
diff --git a/extensions/renderer/v8_schema_registry.cc b/extensions/renderer/v8_schema_registry.cc
index 841c8cf521495b76b16095eefa463dc8dd21be71..c08ca470e03b2d11d979cd4f39eddd52d7e6a2b9 100644
--- a/extensions/renderer/v8_schema_registry.cc
+++ b/extensions/renderer/v8_schema_registry.cc
@@ -29,6 +29,8 @@ class SchemaRegistryNativeHandler : public ObjectBackedNativeHandler {
                              base::Unretained(this)));
   }
 
+  ~SchemaRegistryNativeHandler() override { context_->Invalidate(); }
+
  private:
   void GetSchema(const v8::FunctionCallbackInfo<v8::Value>& args) {
     args.GetReturnValue().Set(