After we replace lid_open_past_180_ with IsMaximizeModeWindowManagerEnabled() in https://codereview.chromium.org/2020553003/ we should further hide EnableMaximizeModeWindowManager() and force all state change through {Enter|Exit}MaximizeMode() instead. Comments from @flackr:

"""
Unfortunately IsMaximizeModeWindowManagerEnabled is not synonymous with
lid_open_past_180_. If we want to make this change we should remove
EnableMaximizeModeWindowManager and force all state changes through
(Enter|Exit)MaximizeMode instead. I do think this is a worthwhile cleanup -
having the separate state for testing code is really messy. We can even remove
the keyboard shortcut for touchview testing.

What will happen is with this change, when you enable the touchview testing flag
and use the keyboard shortcut to enable touchview
(https://cs.chromium.org/chromium/src/ash/accelerators/accelerator_controller....)
we won't disable the keyboard and touchpad when the lid is opened past 180
degrees.
"""