Revert of [Sync] Refactoring polling to be reliable.

components/sync_driver/sync_prefs.cc

Index: components/sync_driver/sync_prefs.cc
diff --git a/components/sync_driver/sync_prefs.cc b/components/sync_driver/sync_prefs.cc
index 77f290d55861203c260c7c3e2c4609787207ceca..c28a2134589bed0159cec23ab827b2da693df5c2 100644
--- a/components/sync_driver/sync_prefs.cc
+++ b/components/sync_driver/sync_prefs.cc
@@ -38,7 +38,6 @@
   registry->RegisterBooleanPref(prefs::kSyncHasSetupCompleted, false);
   registry->RegisterBooleanPref(prefs::kSyncSuppressStart, false);
   registry->RegisterInt64Pref(prefs::kSyncLastSyncedTime, 0);
-  registry->RegisterInt64Pref(prefs::kSyncLastPollTime, 0);
   registry->RegisterInt64Pref(prefs::kSyncFirstSyncTime, 0);
 
   // All datatypes are on by default, but this gets set explicitly
@@ -96,7 +95,6 @@
 void SyncPrefs::ClearPreferences() {
   DCHECK(CalledOnValidThread());
   pref_service_->ClearPref(prefs::kSyncLastSyncedTime);
-  pref_service_->ClearPref(prefs::kSyncLastPollTime);
   pref_service_->ClearPref(prefs::kSyncHasSetupCompleted);
   pref_service_->ClearPref(prefs::kSyncEncryptionBootstrapToken);
   pref_service_->ClearPref(prefs::kSyncKeystoreEncryptionBootstrapToken);
@@ -145,17 +143,6 @@
 void SyncPrefs::SetLastSyncedTime(base::Time time) {
   DCHECK(CalledOnValidThread());
   pref_service_->SetInt64(prefs::kSyncLastSyncedTime, time.ToInternalValue());
-}
-
-base::Time SyncPrefs::GetLastPollTime() const {
-  DCHECK(CalledOnValidThread());
-  return base::Time::FromInternalValue(
-      pref_service_->GetInt64(prefs::kSyncLastSyncedTime));
-}
-
-void SyncPrefs::SetLastPollTime(base::Time time) {
-  DCHECK(CalledOnValidThread());
-  pref_service_->SetInt64(prefs::kSyncLastPollTime, time.ToInternalValue());
 }
 
 bool SyncPrefs::HasKeepEverythingSynced() const {