function getViewStateContext() {
        var projectRoot = ProjectManager.getProjectRoot();  // note: null during unit tests!
        return { location : { scope: "user",
                              layer: "project",
                              layerID: projectRoot && projectRoot.fullPath } };
    }
Returns a 'context' object for getting/setting project-specific view state preferences.
Similar to code in MultiRangeInlineEditor._getPrefsContext()...