Did a bit more digging using the oxygen build. The cursor is still set to 0 (kCursorNull) as well, however on X11 that is equivalent to XUndefineCursor which sets the cursor to the default cursor. This seems to be the same behavior on Windows.

Perhaps the cursor should be initialized to kCursorNone, then setting the cursor to kCursorNull may show a cursor, though I'd have to test and see how the cursor bitmap is defined for kCursorNull.

I'm taking this since I've got 2 changes that should fix this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/122c5365e8b55824410d1e6ba232f2e3871827f9

commit 122c5365e8b55824410d1e6ba232f2e3871827f9
Author: dnicoara <dnicoara@chromium.org>
Date: Wed Apr 06 17:22:44 2016

Wire up cursor proxy on MUS

BUG= 600811 

Review URL: https://codereview.chromium.org/1863113002

Cr-Commit-Position: refs/heads/master@{#385491}

[modify] https://crrev.com/122c5365e8b55824410d1e6ba232f2e3871827f9/ui/ozone/platform/drm/mus_thread_proxy.cc
[modify] https://crrev.com/122c5365e8b55824410d1e6ba232f2e3871827f9/ui/ozone/platform/drm/ozone_platform_gbm.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c82ddf12fd204b7ad9d684049f32ee42952a66f7

commit c82ddf12fd204b7ad9d684049f32ee42952a66f7
Author: dnicoara <dnicoara@chromium.org>
Date: Thu Apr 07 18:15:44 2016

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: refs/heads/master@{#385809}

[modify] https://crrev.com/c82ddf12fd204b7ad9d684049f32ee42952a66f7/components/mus/ws/display.cc

Bulk verified