[Mac] Disable all sandboxd logging unless running with --enable-sandbox-logging.

chrome/common/common.sb

 ;;
 ;; Copyright (c) 2010 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 configuration file isn't used on it's own, but instead implicity included
-; at the start of all other sandbox configuration files in Chrome.
+; This configuration file isn't used on it's own, but instead implicitly
+; included at the start of all other sandbox configuration files in Chrome.
 (version 1)
-(deny default)
+
+; DISABLE_SANDBOX_DENIAL_LOGGING expands to syntax that turns off log message
+; printing on sandbox exceptions; this functionality only exists on 10.6. The
+; --enable-sandbox-logging flag or system versions <10.6 cause this flag to
+; expand to an empty string. http://crbug.com/26621
+(deny default DISABLE_SANDBOX_DENIAL_LOGGING)
 
 ; Support for programmatically enabling verbose debugging.
 ;ENABLE_LOGGING (debug deny)
 
 ; Allow sending signals to self - http://crbug.com/20370
 (allow signal (target self))
 
 ; Needed for full-page-zoomed controls - http://crbug.com/11325
 (allow sysctl-read)
 
 ; Each line is marked with the System version that needs it.
 ; This profile is tested with the following system versions:
 ;     10.5.6, 10.6
 
 ; Allow following symlinks
 (allow file-read-metadata)  ; 10.5.6
 
 ; Loading System Libraries.
 (allow file-read-data (regex #"^/System/Library/Frameworks($|/)"))  ; 10.5.6
 (allow file-read-data (regex #"^/System/Library/PrivateFrameworks($|/)"))  ; 10.5.6
 (allow file-read-data (regex #"^/System/Library/CoreServices($|/)"))  ; 10.5.6
 
 ; Needed for IPC on 10.6
 ;10.6_ONLY (allow ipc-posix-shm)