Split //ui/events/devices into two targets.

ui/platform_window/x11/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
 import("//ui/ozone/ozone.gni")
 
 assert(use_x11 || ozone_platform_x11)
 
 component("x11") {
   output_name = "x11_window"
 
   deps = [
     "//base",
     "//skia",
     "//ui/events",
     "//ui/events/devices",
+    "//ui/events/devices/x11",
     "//ui/events/platform",
     "//ui/events/platform/x11",
     "//ui/gfx/x",
     "//ui/platform_window",
   ]
 
   configs += [ "//build/config/linux:x11" ]
 
   defines = [ "X11_WINDOW_IMPLEMENTATION" ]
 
@@ skipping 13 matching lines @@
       "x11_window_ozone.h",
     ]
     deps += [ "//ui/base" ]
   } else if (use_x11) {
     sources += [
       "x11_window.cc",
       "x11_window.h",
     ]
   }
 }