Rename wm_core_export.h to wm_export.h and the wm_core target to just wm

ui/chromeos/ui_chromeos.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_chromeos',
       'type': '<(component)',
       'dependencies': [
         '../../base/base.gyp:base',
         '../events/events.gyp:events',
-        '../wm/wm.gyp:wm_core',
+        '../wm/wm.gyp:wm',
       ],
       'defines': [
         'UI_CHROMEOS_IMPLEMENTATION',
       ],
       'sources': [
         'user_activity_notifier.cc',
         'user_activity_notifier.h',
       ],
     },
   ],
 }