Add osmesa dependency on events_unittests.

ui/events/events.gyp

 # Copyright 2013 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': [
     {
@@ skipping 283 matching lines @@
     {
       # GN version: //ui/events:events_unittests
       'target_name': 'events_unittests',
       'type': '<(gtest_target_type)',
       'dependencies': [
         '<(DEPTH)/base/base.gyp:base',
         '<(DEPTH)/base/base.gyp:run_all_unittests',
         '<(DEPTH)/base/base.gyp:test_support_base',
         '<(DEPTH)/skia/skia.gyp:skia',
         '<(DEPTH)/testing/gtest.gyp:gtest',
+        '<(DEPTH)/third_party/mesa/mesa.gyp:osmesa',
         '../gfx/gfx.gyp:gfx',
         '../gfx/gfx.gyp:gfx_geometry',
         '../gfx/gfx.gyp:gfx_test_support',
         'devices/events_devices.gyp:events_devices',
         'dom4_keycode_converter',
         'events',
         'events_base',
         'events_test_support',
         'gesture_detection',
         'platform/events_platform.gyp:events_platform',
@@ skipping 114 matching lines @@
               'dependencies': [
                 '../../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }