x11: Use opaque window for dnd without composite.

x11: Use opaque window for dnd without composite.

Use an opaque window for drag and drop when a compositing manager is
absent. Otherwise, the drag and drop window is displayed black.

BUG=712896
Change-Id: I753cc26f5713579e3fc6ffbd952c62ee44d9ae44
Reviewed-on: https://chromium-review.googlesource.com/481103
Reviewed-by: Kenneth Russell <kbr@chromium.org>;
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>;
Reviewed-by: Elliot Glaysher <erg@chromium.org>;
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>;
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>;
Cr-Original-Commit-Position: refs/heads/master@{#466468}(cherry picked from commit 4dc0ad690ed3a08c56b78b0f679580f74d3acf73)
Review-Url: https://codereview.chromium.org/2838753002 .
Cr-Commit-Position: refs/branch-heads/3071@{#179}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/c3cfef7a2bafdb9753d97e01f544f9ab2083bc3c

[sunnyps, 2017-04-24 21:13:54]

Description was changed from

==========
x11: Use opaque window for dnd without composite.

Use an opaque window for drag and drop when a compositing manager is
absent. Otherwise, the drag and drop window is displayed black.

BUG=712896

Change-Id: I753cc26f5713579e3fc6ffbd952c62ee44d9ae44
Reviewed-on: https://chromium-review.googlesource.com/481103
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Elliot Glaysher <erg@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#466468}(cherry picked from commit
4dc0ad690ed3a08c56b78b0f679580f74d3acf73)
==========

to

==========
x11: Use opaque window for dnd without composite.

Use an opaque window for drag and drop when a compositing manager is
absent. Otherwise, the drag and drop window is displayed black.

BUG=712896

Change-Id: I753cc26f5713579e3fc6ffbd952c62ee44d9ae44
Reviewed-on: https://chromium-review.googlesource.com/481103
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Elliot Glaysher <erg@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#466468}(cherry picked from
commit 4dc0ad690ed3a08c56b78b0f679580f74d3acf73)
Review-Url: https://codereview.chromium.org/2838753002 .
Cr-Commit-Position: refs/branch-heads/3071@{#179}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/c3cfef7a2bafdb9753d97e01f544...
==========

[sunnyps, 2017-04-24 21:13:56]

Committed patchset #1 (id:1) manually as
c3cfef7a2bafdb9753d97e01f544f9ab2083bc3c.