Fix security vulnerability allowing apps to start from background Bug: 317048338 Test: Using the steps in b/317048338#comment12 (cherry picked from commit c5fc8ea92c0aabbb2fdccc23b743c18a8bf62e64) (cherry picked from https://googleplex-android-review.googlesource.com/q/commit:df3584bb93ab89d7e174f7d39e42d4b22cb92fe0) Merged-In: Ia91199fdb23beed27bde687fdca8fe5d3a5a4759 Change-Id: Ia91199fdb23beed27bde687fdca8fe5d3a5a4759