function RegistryViewModel() {
        ExtensionManagerViewModel.call(this);
        this.infoMessage = Strings.REGISTRY_SANITY_CHECK_WARNING;
    }
The model for the ExtensionManagerView that is responsible for handling registry-based extensions.
This extends ExtensionManagerViewModel.
Must be disposed with dispose() when done.

Events:
- change - triggered when the data for a given extension changes. Second parameter is the extension id.
- filter - triggered whenever the filtered set changes (including on initialize).

@constructor