Add DCHECK for nullptr in gl bindings

ui/gl/generate_bindings.py

 #!/usr/bin/env python
 # 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.
 
 """code generator for GL/GLES extension wrangler."""
 
 import optparse
 import os
 import collections
@@ skipping 2156 matching lines @@
     log_argument_names = log_argument_names.replace(',', ' << ", " <<')
     if argument_names == 'void' or argument_names == '':
       argument_names = ''
       log_argument_names = ''
     else:
       log_argument_names = " << " + log_argument_names
     function_name = func['known_as']
     if return_type == 'void':
       file.write('  GL_SERVICE_LOG("%s" << "(" %s << ")");\n' %
           (function_name, log_argument_names))
+      file.write('  DCHECK(g_driver_%s.debug_fn.%sFn != nullptr);\n' %
+          (set_name.lower(), function_name))
       file.write('  g_driver_%s.debug_fn.%sFn(%s);\n' %
           (set_name.lower(), function_name, argument_names))
       if 'logging_code' in func:
         file.write("%s\n" % func['logging_code'])
       if options.generate_dchecks and set_name == 'gl':
         file.write('  {\n')
         file.write('    GLenum error = g_driver_gl.debug_fn.glGetErrorFn();\n')
         file.write('    DCHECK(error == 0);\n')
         file.write('  }\n')
     else:
       file.write('  GL_SERVICE_LOG("%s" << "(" %s << ")");\n' %
           (function_name, log_argument_names))
+      file.write('  DCHECK(g_driver_%s.debug_fn.%sFn != nullptr);\n' %
+          (set_name.lower(), function_name))
       file.write('  %s result = g_driver_%s.debug_fn.%sFn(%s);\n' %
           (return_type, set_name.lower(), function_name, argument_names))
       if 'logging_code' in func:
         file.write("%s\n" % func['logging_code'])
       else:
         file.write('  GL_SERVICE_LOG("GL_RESULT: " << result);\n')
       if options.generate_dchecks and set_name == 'gl':
         file.write('  {\n')
         file.write('    GLenum _error = g_driver_gl.debug_fn.glGetErrorFn();\n')
         file.write('    DCHECK(_error == 0);\n')
@@ skipping 576 matching lines @@
                                     'gl_enums_implementation_autogen.h'),
                        'wb')
     GenerateEnumUtils(header_file, enum_header_filenames)
     header_file.close()
     ClangFormat(header_file.name)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))