Update the ICU's default timezone in render

content/browser/time_zone_monitor.cc

 // Copyright 2014 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.
 
 #include "content/browser/time_zone_monitor.h"
 
 #include "base/logging.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_process_host.h"
+#include "third_party/icu/source/common/unicode/unistr.h"
+#include "third_party/icu/source/i18n/unicode/timezone.h"
 
 namespace content {
 
 TimeZoneMonitor::TimeZoneMonitor() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
 TimeZoneMonitor::~TimeZoneMonitor() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 }
 
 void TimeZoneMonitor::NotifyRenderers() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+#if defined(OS_CHROMEOS)
+  // On CrOS, ICU's default tz is already set to a new zone. No
+  // need to redetect it with detectHostTimeZone().
+  scoped_ptr<icu::TimeZone> new_zone(icu::TimeZone::createDefault());
+#else
+  icu::TimeZone* new_zone = icu::TimeZone::detectHostTimeZone();
+#if defined(OS_LINUX)
+  // We get here multiple times on Linux per a single tz change, but
+  // want to update the ICU default zone and notify renderer only once.
+  scoped_ptr<icu::TimeZone> current_zone(icu::TimeZone::createDefault());
+  if (*current_zone == *new_zone) {

[jungshik at Google, 2015/04/24 22:40:54]

This will be true and a msg will not go down to renderers even after a tz change
if |TimeZone::createDefault()| is never called in the browser process before.
That's because createDefault() will call detectHostTimeZone() internally in that
case.
 
One (hacky) solution is to call TimeZone::createDefault() early in the browser
process (as we do in every renderer process before sandbox kicks in;
http://goo.gl/zULKAB ). It'll slow down the init time slightly, but it might be
in noise. 

[jungshik at Google, 2015/04/24 22:46:58]

I did this in PS #10. 

+    VLOG(0) << "timezone already updated";
+    delete new_zone;
+    return;
+  }
+#endif
+  icu::TimeZone::adoptDefault(new_zone);
+#endif
+  icu::UnicodeString zone_id;
+  std::string zone_id_str;
+  new_zone->getID(zone_id).toUTF8String(zone_id_str);
+  VLOG(0) << "timezone reset to " << zone_id_str;
   for (RenderProcessHost::iterator iterator =
            RenderProcessHost::AllHostsIterator();
        !iterator.IsAtEnd();
        iterator.Advance()) {
-    iterator.GetCurrentValue()->NotifyTimezoneChange();
+    iterator.GetCurrentValue()->NotifyTimezoneChange(zone_id_str);
   }
 }
 
 }  // namespace content