Refactor the process of choosing validators.

src/trusted/service_runtime/sel_main_chrome.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/trusted/service_runtime/sel_main_chrome.h"
 
 #include "native_client/src/include/portability.h"
 #include "native_client/src/include/portability_io.h"
@@ skipping 144 matching lines @@
     NaClSetCreateMemoryObjectFunc(args->create_memory_object_func);
 
   /* Inject the validation caching interface, if it exists. */
   nap->validation_cache = args->validation_cache;
 
 #if NACL_WINDOWS
   if (args->broker_duplicate_handle_func != NULL)
     NaClSetBrokerDuplicateHandleFunc(args->broker_duplicate_handle_func);
 #endif
 
-  if (getenv("NACL_DANGEROUS_USE_DFA_VALIDATOR") != NULL) {
-    fprintf(stderr, "DANGER! USING THE UNSTABLE DFA VALIDATOR!\n");
-    nap->enable_dfa_validator = 1;
-  }
-
   NaClAppInitialDescriptorHookup(nap);
 
   /*
    * NACL_SERVICE_PORT_DESCRIPTOR and NACL_SERVICE_ADDRESS_DESCRIPTOR
    * are 3 and 4.
    */
 
   /* import IMC handle - used to be "-i" */
   NaClAddImcHandle(nap, args->imc_bootstrap_handle, export_addr_to);
 
@@ skipping 180 matching lines @@
   if (LOAD_OK != errcode) {
     NaClBlockIfCommandChannelExists(nap);
   }
 
  done_ctor:
 
   NaClAllModulesFini();
 
   NaClExit(ret_code);
 }