Remove the WindowsLogoffRace experiment.

chrome/browser/browser_process_impl.cc

 // Copyright (c) 2012 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_process_impl.h"
 
 #include <algorithm>
 #include <map>
 #include <vector>
 
@@ skipping 428 matching lines @@
     waitable_event_.Signal();
 }
 
 bool RundownTaskCounter::TimedWait(const base::TimeDelta& max_time) {
   // Decrement the excess count from the constructor.
   Decrement();
 
   return waitable_event_.TimedWait(max_time);
 }
 
-bool ExperimentUseBrokenSynchronization() {
-  // The logoff behavior used to have a race, whereby it would perform profile
-  // IO writes on the blocking thread pool, but would sycnhronize to the FILE
-  // thread. Windows feels free to terminate any process that's hidden or
-  // destroyed all it's windows, and sometimes Chrome would be terminated
-  // with pending profile IO due to this mis-synchronization.
-  // Under the "WindowsLogoffRace" experiment group, the broken behavior is
-  // emulated, in order to allow measuring what fraction of unclean shutdowns
-  // are due to this bug.
-  const std::string group_name =
-      base::FieldTrialList::FindFullName("WindowsLogoffRace");
-  return group_name == "BrokenSynchronization";
-}
-
 }  // namespace
 
 void BrowserProcessImpl::EndSession() {
-  bool use_broken_synchronization = ExperimentUseBrokenSynchronization();
-
   // Mark all the profiles as clean.
   ProfileManager* pm = profile_manager();
   std::vector<Profile*> profiles(pm->GetLoadedProfiles());
   scoped_refptr<RundownTaskCounter> rundown_counter(new RundownTaskCounter());
   for (size_t i = 0; i < profiles.size(); ++i) {
     Profile* profile = profiles[i];
     profile->SetExitType(Profile::EXIT_SESSION_ENDED);
 
-    if (!use_broken_synchronization)
-      rundown_counter->Post(profile->GetIOTaskRunner().get());
+    rundown_counter->Post(profile->GetIOTaskRunner().get());
   }
 
   // Tell the metrics service it was cleanly shutdown.
   metrics::MetricsService* metrics = g_browser_process->metrics_service();
   if (metrics && local_state()) {
     metrics->RecordStartOfSessionEnd();
 #if !defined(OS_CHROMEOS)
     // MetricsService lazily writes to prefs, force it to write now.
     // On ChromeOS, chrome gets killed when hangs, so no need to
     // commit metrics::prefs::kStabilitySessionEndCompleted change immediately.
     local_state()->CommitPendingWrite();
 
-    if (!use_broken_synchronization)
-      rundown_counter->Post(local_state_task_runner_.get());
+    rundown_counter->Post(local_state_task_runner_.get());
 #endif
   }
 
   // http://crbug.com/125207
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
 
   // We must write that the profile and metrics service shutdown cleanly,
   // otherwise on startup we'll think we crashed. So we block until done and
   // then proceed with normal shutdown.
   //
   // If you change the condition here, be sure to also change
   // ProfileBrowserTests to match.
 #if defined(USE_X11) || defined(OS_WIN)
-  if (use_broken_synchronization) {
-    rundown_counter->Post(
-        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE).get());
-  }
-
   // Do a best-effort wait on the successful countdown of rundown tasks. Note
   // that if we don't complete "quickly enough", Windows will terminate our
   // process.
   //
   // On Windows, we previously posted a message to FILE and then ran a nested
   // message loop, waiting for that message to be processed until quitting.
   // However, doing so means that other messages will also be processed. In
   // particular, if the GPU process host notices that the GPU has been killed
   // during shutdown, it races exiting the nested loop with the process host
   // blocking the message loop attempting to re-establish a connection to the
@@ skipping 700 matching lines @@
 }
 
 void BrowserProcessImpl::OnAutoupdateTimer() {
   if (CanAutorestartForUpdate()) {
     DLOG(WARNING) << "Detected update.  Restarting browser.";
     RestartBackgroundInstance();
   }
 }
 
 #endif  // (defined(OS_WIN) || defined(OS_LINUX)) && !defined(OS_CHROMEOS)