Remove unnecessary TODO comments.

In patch a483f31ce80f1f12fb93e956702fa74ba6ba7bc0, the two comments were
removed. It is still here due to rebase error when removing the
AppWindowContainerController.

Test: go/wm-smoke
Bug: 119530958
Change-Id: I74253f4c57acee039df44fa73c1432df15288dbc
1 file changed