Set last cursor default to kCursorNone
Set last cursor default to kCursorNone

This makes the last set cursor as hidden.

Since MUS is controlling the cursor (and managing the cursor
resources), starting with a hidden cursor is better as MUS can
control the cursor interaction end-to-end.

Also, when running MUS as the display manager, MUS is in charge
of setting the default cursor, so there is no underlying
window manager to set the cursor initially (the initial cursor
state is invisible).

On multi-display configurations the expected behavior is to
start with a hidden cursor on new displays.

BUG=600811

Review URL: https://codereview.chromium.org/1869463002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#385809}

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