Revert of Fixes _NET_ACTIVE_WINDOW support check in order to not always return no. (https://codereview.chromium.org/138903007/)

Reason for revert:
Speculative revert for DesktopScreenX11Test.GetWindowAtScreenPoint test failure on Linux Aura Tests bot:

http://build.chromium.org/p/chromium.linux/builders/Linux%20Aura%20Tests/builds/814/steps/views_unittests/logs/stdio

[ RUN      ] DesktopScreenX11Test.GetWindowAtScreenPoint
Xlib:  extension "RANDR" missing on display ":9".
../../ui/views/widget/desktop_aura/desktop_screen_x11_unittest.cc:227: Failure
Value of: screen()->GetWindowAtScreenPoint(gfx::Point(115, 115))
  Actual: 0x7f84f619fc00
Expected: window_three->GetNativeWindow()
Which is: 0x1fbfcfb82200
[  FAILED  ] DesktopScreenX11Test.GetWindowAtScreenPoint (82 ms)

Original issue's description:
> Fixes _NET_ACTIVE_WINDOW support check in order to not always return no.
> 
> The check is currently not working on Unity because it expects an array
> of atoms instead of one XID. With this patch, Unity is correctly seen
> as supporting the feature.
> 
> BUG=None
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=246270

TBR=erg@chromium.org,mlamouri@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=None

Review URL: https://codereview.chromium.org/144003015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246309 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246309