[Merge to M62] Revert "X11: Fix transparency on certain windows"

> This reverts commit cd8bc9f.
>
> Reason for revert: Breaks thestig@'s theme.  Also, ShouldWindowContentsBeTransparent() should only return true on the Windows Aero theme
>
> Original change's description:
> > X11: Fix transparency on certain windows
> >
> > Transparency on arrow windows stopped working after CL [1].  This CL
> > is a one-line selective revert of that CL.  Note that transparency on
> > all other windows that I've tested (drag images, dragged URLs, etc)
> > were not broken.
> >
> > [1] https://chromium.googlesource.com/chromium/src/+/5785866a9b2a0db4854552eb87af7229d4b11a43
> >
> > BUG=758304
> > R=​erg@chromium.org
> >
> > Change-Id: I37020d930bd081facce65b0a8be0eeb2e1756c69
> > Reviewed-on: https://chromium-review.googlesource.com/629538
> > Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
> > Reviewed-by: Elliot Glaysher <erg@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#496775}
>
> TBR=erg@chromium.org,thomasanderson@chromium.org
>
> # Not skipping CQ checks because original CL landed > 1 day ago.
>
> Bug: 758304
> Change-Id: I5fa80e041c77d485afa08dea99d893f84474c458
> Reviewed-on: https://chromium-review.googlesource.com/647032
> Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
> Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#499131}
>

BUG=758304
TBR=erg@chromium.org
CC=thestig@chromium.org
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true

Change-Id: I5e69899078d27d1b24b95ee2d02a84a8db6270ee
Reviewed-on: https://chromium-review.googlesource.com/648089
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/branch-heads/3202@{#6}
Cr-Branched-From: fa6a5d8-refs/heads/master@{#499098}

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

@@ -974,7 +974,7 @@ bool DesktopWindowTreeHostX11::ShouldUseNativeFrame() const {
 }
 
 bool DesktopWindowTreeHostX11::ShouldWindowContentsBeTransparent() const {
-  return IsTranslucentWindowOpacitySupported();
+  return false;
 }
 
 void DesktopWindowTreeHostX11::FrameTypeChanged() {