Use only timezone IDs from known timezone list.

chrome/browser/chromeos/dom_ui/system_settings_provider.cc

 // 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.
 
 #include "chrome/browser/chromeos/dom_ui/system_settings_provider.h"
 
 #include <string>
 
 #include "app/l10n_util.h"
 #include "base/i18n/rtl.h"
@@ skipping 196 matching lines @@
     const icu::TimeZone* timezone = GetTimezone(value);
     if (!timezone)
       return;
     CrosLibrary::Get()->GetSystemLibrary()->SetTimezone(timezone);
   }
 }
 
 bool SystemSettingsProvider::Get(const std::string& path,
                                  Value** out_value) const {
   if (path == kSystemTimezone) {
-    *out_value = Value::CreateStringValue(
-        GetTimezoneID(CrosLibrary::Get()->GetSystemLibrary()->GetTimezone()));
+    *out_value = Value::CreateStringValue(GetKnownTimezoneID(
+        CrosLibrary::Get()->GetSystemLibrary()->GetTimezone()));
     return true;
   }
   return false;
 }
 
 bool SystemSettingsProvider::HandlesSetting(const std::string& path) {
   return ::StartsWithASCII(path, std::string("cros.system."), true);
 }
 
 void SystemSettingsProvider::TimezoneChanged(const icu::TimeZone& timezone) {
@@ skipping 64 matching lines @@
   for (std::vector<icu::TimeZone*>::iterator iter = timezones_.begin();
        iter != timezones_.end(); ++iter) {
     const icu::TimeZone* timezone = *iter;
     if (GetTimezoneID(*timezone) == timezone_id) {
       return timezone;
     }
   }
   return NULL;
 }
 
+string16 SystemSettingsProvider::GetKnownTimezoneID(
+    const icu::TimeZone& timezone) const {
+  for (std::vector<icu::TimeZone*>::const_iterator iter = timezones_.begin();
+       iter != timezones_.end(); ++iter) {
+    const icu::TimeZone* known_timezone = *iter;
+    if (known_timezone->hasSameRules(timezone))
+      return GetTimezoneID(*known_timezone);
+  }
+
+  // Not able to find a matching timezone in our list.
+  return string16();
+}
+
 }  // namespace chromeos