Revert "Unify context in ViewRoot"

This reverts commit 44f5215ee81d7406b6fb7b1fa0c95f106a35f618.

Reason for revert: <Make Ime test in SystemDecorationTest failed>
Bug: 130715649

Change-Id: I9afb1d5ee7e7a4f1e7de6fa4c7c3ec5dcc336f08
3 files changed