Starting activity failed and the mFocusedActvity become null,
consider this condition when adjust focus.
Because in this condition, the focus mismatch between
ActivityManagerService#mFocusedActivity and
InputDispatcher(inputfilnger)#mFocusedApplication, ANR may occur.
Test: monkey test 48h with no ANR
Change-Id: Id1a2bf0d6ca6530e34443d359fbe2aa6c11b878c