Revert "Remove redundant IMM#mServedInputConnection."

This reverts commit afb6558c8f5e0ee797b252558d7e529e3d946d8f.

It turns out that this CL caused a serious regression Bug 27824691.

Bug: 25332806
Bug: 27824691
Change-Id: I16312592743a6673449c492ee5ba533256d343ea
2 files changed