Revert "Bug#982491 Group apps in activities chains in the same process a=fabrice, check whether detail.extra was null"

This reverts commit 81437e4b9d509dcd739a5355cb2becf66e6140ce.
Revert "Bug#982491 Group apps in activities chains in the same process a=fabrice"

This reverts commit b0d05385700f7998e0736d3a3749d10fda5d46c2.