Refactor the process of choosing validators.

src/trusted/validator/x86/ncval_seg_sfi/ncdecode.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.
  */
 
 /*
  * ncdecode.c - table driven decoder for Native Client
  *
  * Most x86 decoders I've looked at are big case statements. While
@@ skipping 667 matching lines @@
 
 /* Default action for a decoder state pair. */
 static Bool NullNCDecoderStatePairAction(struct NCDecoderStatePair* tthis,
                                          NCDecoderInst* old_inst,
                                          NCDecoderInst* new_inst) {
   return TRUE;
 }
 
 void NCDecoderStatePairConstruct(NCDecoderStatePair* tthis,
                                  NCDecoderState* old_dstate,
-                                 NCDecoderState* new_dstate) {
+                                 NCDecoderState* new_dstate,
+                                 NaClCopyInstructionFunc copy_func) {
   tthis->old_dstate = old_dstate;
   tthis->new_dstate = new_dstate;
   tthis->action_fn = NullNCDecoderStatePairAction;
+  tthis->copy_func = copy_func;
 }
 
 void NCDecoderStatePairDestruct(NCDecoderStatePair* tthis) {
 }
 
 Bool NCDecoderStatePairDecode(NCDecoderStatePair* tthis) {
   NCDecoderInst* old_dinst =
       &tthis->old_dstate->inst_buffer[tthis->old_dstate->cur_inst_index];
   NCDecoderInst* new_dinst =
       &tthis->new_dstate->inst_buffer[tthis->new_dstate->cur_inst_index];
@@ skipping 62 matching lines @@
     if (! (tthis->action_fn)(tthis, old_dinst, new_dinst)) {
       return FALSE;
     }
 
     /* Move to next instruction. */
     old_dinst = IncrementInst(old_dinst);
     new_dinst = IncrementInst(new_dinst);
   }
   return TRUE;
 }