Pass IWindow to InputWindowHandle.

This allows listeners to identify which WindowInfo belongs to which
IWindow. Using InputChannel token may not work since not every Window
has an InputChannel, but every window should have an IWindow token.
There may still be WindowInfo data that doesn't contain an IWindow token
if they were created as pure layers, and not windows.

Test: IWindow token sent to listeners
Bug: 188792659
Change-Id: Ie90453d40906c0ee8312a23a6f4c8e85310bbaf7