Check NaCl debug mask (not just flag) before choosing PNaCl debug URL.

ppapi/api/private/ppb_nacl_private.idl

 /* 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.
  */
 
 /* This file contains NaCl private interfaces. This interface is not versioned
  * and is for internal Chrome use. It may change without notice. */
 
 label Chrome {
   M25 = 1.0
@@ skipping 266 matching lines @@
                        [in] str_t error_message,
                        [in] str_t console_message,
                        [in] PP_Bool is_installed);
 
   /* Performs internal setup when an instance is created. */
   void InstanceCreated([in] PP_Instance instance);
 
   /* Performs internal cleanup when an instance is destroyed. */
   void InstanceDestroyed([in] PP_Instance instance);
 
-  /* Return true if the NaCl debug stub is enabled and the loaded app
-   * will be attached to a debugger.
+  /* Return true if the NaCl debug stub is enabled and the app loaded from
+   * alleged_nmf_url will be attached to a debugger.
    */
-  PP_Bool NaClDebugStubEnabled();
+  PP_Bool NaClDebugEnabledForURL([in] str_t alleged_nmf_url);
 
   /* Returns the kind of SFI sandbox implemented by NaCl on this
   /* platform.
    */
   str_t GetSandboxArch();
 
   /* Returns the scheme type for a given url. */
   PP_UrlSchemeType GetUrlScheme([in] PP_Var url);
 
   /* Logs the message to the console. */
   void LogToConsole([in] PP_Instance instance,
                     [in] str_t message);
 };