Linux: use generated shim headers for system mesa.

third_party/mesa/mesa.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': {
     # Disable warnings as errors for mesa until they're fixed or disabled.
     # http://crbug.com/143877
     'win_third_party_warn_as_error': 'false',
-
-    'use_system_mesa%': 0,
   },
   'conditions': [
     ['use_system_mesa==0', {
       'target_defaults': {
         'conditions': [
           ['OS!="win"', {
             'defines': [
               # For talloc
               'HAVE_VA_COPY',
             ],
@@ skipping 563 matching lines @@
             'MesaLib/src/mesa/drivers/osmesa/osmesa.def',
           ],
         },
       ],
     }, { # use_system_mesa==1
       'targets': [
         # TODO(phajdan.jr): Make this work, http://crbug.com/161389 .
         {
           'target_name': 'mesa_headers',
           'type': 'none',
+          'variables': {
+            'headers_root_path': 'MesaLib/include',
+            # This list can easily be updated using the command below:
+            # find third_party/mesa/MesaLib/include -iname '*.h' \
+            # -printf "'%p',\n" | grep -v internal | sed -e \
+            # 's|third_party/mesa/MesaLib/include/||' | sort -u
+            'header_filenames': [
+              'GL/glext.h',
+              'GL/glfbdev.h',
+              'GL/gl.h',
+              'GL/gl_mangle.h',
+              'GL/glu.h',
+              'GL/glu_mangle.h',
+              'GL/glxext.h',
+              'GL/glx.h',
+              'GL/glx_mangle.h',
+              'GL/mesa_wgl.h',
+              'GL/osmesa.h',
+              'GL/vms_x_fix.h',
+              'GL/wglext.h',
+              'GL/wmesa.h',
+            ],
+          },
+          'includes': [
+            '../../build/shim_headers.gypi',
+          ],
         },
         {
           'target_name': 'mesa',
           'type': 'none',
         },
         {
           'target_name': 'osmesa',
           'type': 'none',
         },
       ],
     }],
   ],
 }