When WindowManagerService.mInTouchMode is changed, we will set the new
mode to InputManagerService, and clients will be notified via
ViewRootImpl.WindowInputEventReceiver#onTouchModeChanged. We don't need
the flag to bring the information to the client.
This is also a step to make relayout an oneway binder call.
Bug: 161810301
Test: Invoke View#requestFocusFromTouch on one window and see if another
window can receive OnTouchModeChangeListener#onTouchModeChanged.
Change-Id: Ic149c95bee89b2be83a85eb4858131224b63a7c8
3072d027ec