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

ui/events/events.gyp

Index: ui/events/events.gyp
diff --git a/ui/events/events.gyp b/ui/events/events.gyp
index c8d994f5e4b7dfa9c59b8663437a115f67afb729..cf1ed63a4a0e89919514533b551b492cec7962b4 100644
--- a/ui/events/events.gyp
+++ b/ui/events/events.gyp
@@ -162,6 +162,7 @@
             '../../build/linux/system.gyp:x11',
             '../gfx/x/gfx_x11.gyp:gfx_x11',
             'devices/events_devices.gyp:events_devices',
+            'devices/x11/events_devices_x11.gyp:events_devices_x11',
             'x/events_x.gyp:events_x',
           ],
         }],
@@ -362,6 +363,11 @@
           # The cocoa files don't apply to iOS.
           'sources/': [['exclude', 'cocoa']],
         }],
+        ['use_x11==1', {
+          'dependencies': [
+            'devices/x11/events_devices_x11.gyp:events_devices_x11',
+          ],
+        }],
         ['use_x11==1 or use_ozone==1', {
           'sources' : [
               'test/device_data_manager_test_api_impl.cc',