Revert^2 "Migrate FocusEventDebugView to an input subpackage."

This reverts commit bbf6d4e5.

Reason for revert: undo initial revert with fix. There was some
class/method visibility issue that was causing test failures. Making
the classes/methods public+hidden to avoid the test failures.

Change-Id: Ib3d85c47c596a6290abc66f2ec6e4d4e5f65297c