Broadcast NotifyTimezoneChange to all RenderProcessHosts when the system time zone changes

content/renderer/renderer.sb

 ;;
 ;; Copyright (c) 2011 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.
 ;;
 
 ; *** The contents of content/common/common.sb are implicitly included here. ***
 
 ; Needed for Fonts.
 (allow file-read* (regex #"^/System/Library/Fonts($|/)"))  ; 10.5.6
@@ skipping 11 matching lines @@
 )
 
 ; http://crbug.com/11269
 (allow file-read* (subpath "@USER_HOMEDIR_AS_LITERAL@/Library/Fonts"))  ; 10.6
 
 ; http://crbug.com/60917
 (allow file-read-metadata
   (literal "/")
   (literal "/var")
 )
+
+; http://crbug.com/288697

[jeremy, 2014/04/29 11:50:52]

I assume there is no way to add code to sandbox warmup so we don't need to add
stuff to the sandbox profile? I'd prefer that approach if feasible...

IIUC this is just a temporary hole and we can close it once things are plumbed
through from the browser correctly?  If so can you specifically mention this in
the comment here?

[Mark Mentovai, 2014/04/29 13:00:40]

jeremy wrote:
The time zone is already warmed up at renderer startup. The problem is that if
the time zone changes, renderer processes need to read the new time zone
specification, because the one that they’ve cached will have become invalid.
Not so. I don’t have any plans to plumb this through to the browser on any
additional platforms, and even on Linux where this currently does happen, Julien
considers it a hack and has said he’d like to remove it.

localtime is normally a fast library call. If we took the approach of plumbing
it through to the browser, each localtime call would become a blocking IPC.
There are also likely numerous calls to localtime, mostly in third_party code,
and we’d have to hack away at all of it to replace localtime in these cases.

I looked at solutions involving bringing the new time zone definition into the
renderer when it changes, but couldn’t arrive at anything good. The standardized
formats for the TZ environment variable aren’t rich enough to provide a full
time zone specification, and the nonstandard format observed by Mac and glibc
allows a full time zone specification to be read from a file, but that’s not
useful in renderer processes.

+(allow file-read*
+  (regex #"^/(private/)?etc/localtime$")
+  (regex #"^/usr/share/zoneinfo/")
+)
+(allow file-read-metadata
+  (regex #"^/(private/)?etc$")
+)