[Temp] Backport r261058 from Chromium.

  Replace #ifdef(OS_LINUX) with #ifdef(USE_X11) for x11 specific code

  This fixes the Ozone FYI builder.

  https://codereview.chromium.org/213283004 added X11 specific code but
  uses OS_LINUX to enable it. The Ozone build is a linux build but
  without X11, thus failing tests.

  TESTS=Manually ran content_browsertests content_unittests
  components_unittests with an Ozone build

  Review URL: https://codereview.chromium.org/217323008
[Temp] Backport r262370 from Chromium.

  We use TextEditKeyBindingsDelegate and TextEditCommand for x11. These
  classes don't have any x11 specific dependencies. This CL adds support
  to use them for all platforms on Linux.

  This fixes linking error when building Chromium with Ozone.

  Review URL: https://codereview.chromium.org/225583005
Merge pull request #157 from rakuco/ozone-fix-backports

Backport Chromium commits to fix the Ozone build with 35.0.1916.114.