[wm] Use existing parent window token for child windows

The child windows should be attached to the parent window rather than its window token.
The window token can be visible state only if it has child containers.
So, if the window token is created only for the child window, then it cannot be visible state.

Test: atest WmTests:WindowTokenTests
Change-Id: I3efa14fda7a5674a178b13ff6310a526e75e3b50
2 files changed