Remove IMMS#MSG_CREATE_SESSION

This CL inlines

  InputMethodManagerService#MSG_CREATE_SESSION

handler as it has always been executed from the calling thread.

There should be no observable behavior change.

Bug: 215609403
Test: presubmit
Change-Id: I870039f38cd1de3908811cc7fc1d5c88d1f0406b
1 file changed