content/browser/time_zone_monitor.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_TIME_ZONE_MONITOR_H_
   6 #define CONTENT_BROWSER_TIME_ZONE_MONITOR_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/scoped_ptr.h"
  10
  11 namespace content {
  12
  13 // TimeZoneMonitor watches the system time zone, and notifies renderers
  14 // when it changes. Some renderer code caches the system time zone, so
  15 // this notification is necessary to inform such code that cached
  16 // timezone data may have become invalid. Due to sandboxing, it is not
  17 // possible for renderer processes to monitor for system time zone
  18 // changes themselves, so this must happen in the browser process.
  19 //
  20 // Sandboxing also may prevent renderer processes from reading the time
  21 // zone when it does change, so platforms may have to deal with this in
  22 // platform-specific ways:
  23 //  - Mac uses a sandbox hole defined in content/renderer/renderer.sb.
  24 //  - Linux-based platforms use ProxyLocaltimeCallToBrowser in
  25 //    content/zygote/zygote_main_linux.cc and HandleLocaltime in
  26 //    content/browser/renderer_host/sandbox_ipc_linux.cc to override
  27 //    localtime in renderer processes with custom code that calls
  28 //    localtime in the browser process via Chrome IPC.
  29
  30 class TimeZoneMonitor {
  31  public:
  32   // Returns a new TimeZoneMonitor object (likely a subclass) specific to the
  33   // platform.
  34   static scoped_ptr<TimeZoneMonitor> Create();
  35
  36   virtual ~TimeZoneMonitor();
  37
  38  protected:
  39   TimeZoneMonitor();
  40
  41   // Loop over all renderers and notify them that the system time zone may
  42   // have changed.
  43   void NotifyRenderers();
  44
  45  private:
  46   DISALLOW_COPY_AND_ASSIGN(TimeZoneMonitor);
  47 };
  48
  49 }  // namespace content
  50
  51 #endif  // CONTENT_BROWSER_TIME_ZONE_MONITOR_H_