/usr/include/KF5/webengineviewer/ is in libkf5webengineviewer-dev 4:17.12.3-0ubuntu3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/webengineviewer/checkphishingurlcache.h
/usr/include/KF5/webengineviewer/checkphishingurljob.h
/usr/include/KF5/webengineviewer/checkphishingurlutil.h
/usr/include/KF5/webengineviewer/createphishingurldatabasejob.h
/usr/include/KF5/webengineviewer/findbarbase.h
/usr/include/KF5/webengineviewer/findbarwebengineview.h
/usr/include/KF5/webengineviewer/hashcachemanager.h
/usr/include/KF5/webengineviewer/interceptormanager.h
/usr/include/KF5/webengineviewer/localdatabasemanager.h
/usr/include/KF5/webengineviewer/networkpluginurlinterceptor.h
/usr/include/KF5/webengineviewer/networkpluginurlinterceptorconfigurewidget.h
/usr/include/KF5/webengineviewer/networkpluginurlinterceptorinterface.h
/usr/include/KF5/webengineviewer/networkurlinterceptor.h
/usr/include/KF5/webengineviewer/networkurlinterceptorpluginmanager.h
/usr/include/KF5/webengineviewer/searchfullhashjob.h
/usr/include/KF5/webengineviewer/updatedatabaseinfo.h
/usr/include/KF5/webengineviewer/webengineaccesskey.h
/usr/include/KF5/webengineviewer/webengineexporthtmlpagejob.h
/usr/include/KF5/webengineviewer/webenginemanagescript.h
/usr/include/KF5/webengineviewer/webenginepage.h
/usr/include/KF5/webengineviewer/webenginescript.h
/usr/include/KF5/webengineviewer/webengineview.h
/usr/include/KF5/webengineviewer/webengineviewer_export.h
/usr/include/KF5/webengineviewer/webhittest.h
/usr/include/KF5/webengineviewer/webhittestresult.h
/usr/include/KF5/webengineviewer/zoomactionmenu.h