[bindings] Implement an ExperimentEnabled IDL extended attribute.

third_party/WebKit/Source/bindings/scripts/code_generator_v8.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 383 matching lines @@
         # if pre-cached this is read-only, but writing creates a race condition.
         bytecode_cache=jinja2.FileSystemBytecodeCache(cache_dir),
         keep_trailing_newline=True,  # newline-terminate generated files
         lstrip_blocks=True,  # so can indent control flow tags
         trim_blocks=True)
     jinja_env.filters.update({
         'blink_capitalize': capitalize,
         'conditional': conditional_if_endif,
         'exposed': exposed_if,
         'runtime_enabled': runtime_enabled_if,
+        'experiment_enabled': experiment_enabled_if,
         })
     return jinja_env
 
 
 def generate_indented_conditional(code, conditional):
     # Indent if statement to level of original code
     indent = re.match(' *', code).group(0)
     return ('%sif (%s) {\n' % (indent, conditional) +
             '    %s\n' % '\n    '.join(code.splitlines()) +
             '%s}\n' % indent)
@@ skipping 16 matching lines @@
     return generate_indented_conditional(code, 'executionContext && (%s)' % exposed_test)
 
 
 # [RuntimeEnabled]
 def runtime_enabled_if(code, runtime_enabled_function_name):
     if not runtime_enabled_function_name:
         return code
     return generate_indented_conditional(code, '%s()' % runtime_enabled_function_name)
 
 
+# [ExperimentEnabled]
+def experiment_enabled_if(code, experiment_name, error_message):
+    if not experiment_name:
+        return code
+    return generate_indented_conditional(code, 'Experiments::isApiEnabled(currentExecutionContext(isolate), "%s", %s)' % (experiment_name, error_message))
+
 ################################################################################
 
 def main(argv):
     # If file itself executed, cache templates
     try:
         cache_dir = argv[1]
         dummy_filename = argv[2]
     except IndexError as err:
         print 'Usage: %s CACHE_DIR DUMMY_FILENAME' % argv[0]
         return 1
 
     # Cache templates
     jinja_env = initialize_jinja_env(cache_dir)
     template_filenames = [filename for filename in os.listdir(templates_dir)
                           # Skip .svn, directories, etc.
                           if filename.endswith(('.cpp', '.h'))]
     for template_filename in template_filenames:
         jinja_env.get_template(template_filename)
 
     # Create a dummy file as output for the build system,
     # since filenames of individual cache files are unpredictable and opaque
     # (they are hashes of the template path, which varies based on environment)
     with open(dummy_filename, 'w') as dummy_file:
         pass  # |open| creates or touches the file
 
 
 if __name__ == '__main__':
     sys.exit(main(sys.argv))