events: Create a separate platforms target.

ui/base/ui_base.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
       'target_name': 'ui_base',
       'type': '<(component)',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/base.gyp:base_i18n',
         '../../base/base.gyp:base_static',
         '../../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '../../net/net.gyp:net',
         '../../skia/skia.gyp:skia',
         '../../third_party/icu/icu.gyp:icui18n',
         '../../third_party/icu/icu.gyp:icuuc',
         '../../url/url.gyp:url_lib',
         '../events/events.gyp:events_base',
+        '../events/platform/events_platform.gyp:events_platform',
         '../gfx/gfx.gyp:gfx',
         '../gfx/gfx.gyp:gfx_geometry',
         '../resources/ui_resources.gyp:ui_resources',
         'strings/ui_strings.gyp:ui_strings',
       ],
       'defines': [
         'UI_BASE_IMPLEMENTATION',
       ],
       'export_dependent_settings': [
         '../../net/net.gyp:net',
@@ skipping 458 matching lines @@
             'ldflags': [
               '-L<(PRODUCT_DIR)',
             ],
           },
           'dependencies': [
             '../../build/linux/system.gyp:x11',
             '../../build/linux/system.gyp:xcursor',
             '../../build/linux/system.gyp:xext',
             '../../build/linux/system.gyp:xfixes',
             '../../build/linux/system.gyp:xrender',  # For XRender* function calls in x11_util.cc.
+            '../events/platform/x11/x11_events_platform.gyp:x11_events_platform',
           ],
         }],
         ['toolkit_views==0', {
           'sources!': [
             'dragdrop/drag_drop_types.h',
             'dragdrop/drop_target_event.cc',
             'dragdrop/drop_target_event.h',
             'dragdrop/os_exchange_data.cc',
             'dragdrop/os_exchange_data.h',
             'nine_image_painter_factory.cc',
@@ skipping 115 matching lines @@
            ],
            'variables': {
              'jni_gen_package': 'ui',
            },
            'includes': [ '../../build/jni_generator.gypi' ],
          },
        ],
     }],
   ],
 }