Move GLSurfaceOSMesaX11 into it's own source file.

ui/gl/gl.gyp

 # Copyright (c) 2012 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 164 matching lines @@
             'gl_egl_api_implementation.cc',
             'gl_egl_api_implementation.h',
             'gl_glx_api_implementation.cc',
             'gl_glx_api_implementation.h',
             'gl_image_glx.cc',
             'gl_image_glx.h',
             'gl_surface_egl_x11.cc',
             'gl_surface_egl_x11.h',
             'gl_surface_glx.cc',
             'gl_surface_glx.h',
+            'gl_surface_osmesa_x11.cc',
+            'gl_surface_osmesa_x11.h',
           ],
           'direct_dependent_settings': {
             'defines': [
               'GL_GLEXT_PROTOTYPES',
               'USE_GLX',
             ],
           },
           'defines': [
             'USE_GLX',
           ],
@@ skipping 187 matching lines @@
           ],
           'variables': {
             'jni_gen_package': 'ui/gl',
           },
           'includes': [ '../../build/jni_generator.gypi' ],
         },
       ],
     }],
   ],
 }