ThreadRestrictions: disallow blocking IO on the UI thread

chrome/browser/browser_shutdown.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/browser_shutdown.h"
 
 #include <string>
 
 #include "app/resource_bundle.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/metrics/histogram.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/thread.h"
+#include "base/thread_restrictions.h"
 #include "base/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/dom_ui/chrome_url_data_manager.h"
 #include "chrome/browser/first_run/first_run.h"
 #include "chrome/browser/jankometer.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/plugin_process_host.h"
@@ skipping 64 matching lines @@
   }
 }
 
 FilePath GetShutdownMsPath() {
   FilePath shutdown_ms_file;
   PathService::Get(chrome::DIR_USER_DATA, &shutdown_ms_file);
   return shutdown_ms_file.AppendASCII(kShutdownMsFile);
 }
 
 void Shutdown() {
+  // During shutdown we will end up some blocking operations.  But the
+  // work needs to get done and we're going to wait for them no matter
+  // what thread they're on, so don't worry about it slowing down
+  // shutdown.
+  base::ThreadRestrictions::SetIOAllowed(true);
+
   // Unload plugins. This needs to happen on the IO thread.
   BrowserThread::PostTask(
         BrowserThread::IO, FROM_HERE,
         NewRunnableFunction(&ChromePluginLib::UnloadAllPlugins));
 
   // Shutdown all IPC channels to service processes.
   ServiceProcessControlManager::instance()->Shutdown();
 
   // WARNING: During logoff/shutdown (WM_ENDSESSION) we may not have enough
   // time to get here. If you have something that *must* happen on end session,
@@ skipping 187 matching lines @@
 
 bool ShuttingDownWithoutClosingBrowsers() {
 #if defined(USE_X11)
   if (GetShutdownType() == browser_shutdown::END_SESSION)
     return true;
 #endif
   return false;
 }
 
 }  // namespace browser_shutdown