/usr/share/gtk-doc/ is in libsignon-glib-doc 1.14+17.04.20161117-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gtk-doc/html/
/usr/share/gtk-doc/html/libsignon-glib/
/usr/share/gtk-doc/html/libsignon-glib/SignonAuthService.html
/usr/share/gtk-doc/html/libsignon-glib/SignonAuthSession.html
/usr/share/gtk-doc/html/libsignon-glib/SignonIdentity.html
/usr/share/gtk-doc/html/libsignon-glib/SignonIdentityInfo.html
/usr/share/gtk-doc/html/libsignon-glib/annotation-glossary.html
/usr/share/gtk-doc/html/libsignon-glib/api-index-1-8.html
/usr/share/gtk-doc/html/libsignon-glib/api-index-deprecated.html
/usr/share/gtk-doc/html/libsignon-glib/api-index-full.html
/usr/share/gtk-doc/html/libsignon-glib/appendices.html
/usr/share/gtk-doc/html/libsignon-glib/credential-management.html
/usr/share/gtk-doc/html/libsignon-glib/gdbus-com.google.code.AccountsSSO.SingleSignOn.AuthService.html
/usr/share/gtk-doc/html/libsignon-glib/gdbus-com.google.code.AccountsSSO.SingleSignOn.AuthSession.html
/usr/share/gtk-doc/html/libsignon-glib/gdbus-com.google.code.AccountsSSO.SingleSignOn.Identity.html
/usr/share/gtk-doc/html/libsignon-glib/home.png
/usr/share/gtk-doc/html/libsignon-glib/index.html
/usr/share/gtk-doc/html/libsignon-glib/left-insensitive.png
/usr/share/gtk-doc/html/libsignon-glib/left.png
/usr/share/gtk-doc/html/libsignon-glib/libsignon-glib-SignonError.html
/usr/share/gtk-doc/html/libsignon-glib/libsignon-glib-objects.html
/usr/share/gtk-doc/html/libsignon-glib/libsignon-glib-overview.html
/usr/share/gtk-doc/html/libsignon-glib/libsignon-glib.devhelp2
/usr/share/gtk-doc/html/libsignon-glib/object-tree.html
/usr/share/gtk-doc/html/libsignon-glib/right-insensitive.png
/usr/share/gtk-doc/html/libsignon-glib/right.png
/usr/share/gtk-doc/html/libsignon-glib/signond-dbus-api.html
/usr/share/gtk-doc/html/libsignon-glib/style.css
/usr/share/gtk-doc/html/libsignon-glib/up-insensitive.png
/usr/share/gtk-doc/html/libsignon-glib/up.png