Moved JsonPrefStore to use SequencedWorkerPool

chrome/browser/metrics/metrics_service.cc

Index: chrome/browser/metrics/metrics_service.cc
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index 58f398d2fe0359c878f884166df193d7a5b325ce..680e4a591a1c2998217f064bd5316109895021e6 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -1723,27 +1723,11 @@ bool MetricsService::UmaMetricsProperlyShutdown() {
   return clean_shutdown_status_ == CLEANLY_SHUTDOWN;
 }
 
-// For use in hack in LogCleanShutdown.
-static void Signal(base::WaitableEvent* event) {
-  event->Signal();
-}
-
 void MetricsService::LogCleanShutdown() {
   // Redundant hack to write pref ASAP.
   PrefService* pref = g_browser_process->local_state();
   pref->SetBoolean(prefs::kStabilityExitedCleanly, true);
   pref->CommitPendingWrite();
-  // Hack: TBD: Remove this wait.
-  // We are so concerned that the pref gets written, we are now willing to stall
-  // the UI thread until we get assurance that a pref-writing task has
-  // completed.
-  base::WaitableEvent done_writing(false, false);
-  BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-                          base::Bind(Signal, &done_writing));
-  // http://crbug.com/124954
-  base::ThreadRestrictions::ScopedAllowWait allow_wait;
-  done_writing.TimedWait(base::TimeDelta::FromHours(1));
-
   // Redundant setting to assure that we always reset this value at shutdown
   // (and that we don't use some alternate path, and not call LogCleanShutdown).
   clean_shutdown_status_ = CLEANLY_SHUTDOWN;