Revert of DataReductionProxyStatisticsPrefs should support WeakPtr

components/data_reduction_proxy/core/browser/data_reduction_proxy_statistics_prefs.cc

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_statistics_prefs.cc
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_statistics_prefs.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_statistics_prefs.cc
index 1b28d5d7143431b346983af40e954d722b8eca85..93d23208247b5439f56862ef6c273b42c8a54a3b 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_statistics_prefs.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_statistics_prefs.cc
@@ -33,8 +33,12 @@
 }
 
 DataReductionProxyStatisticsPrefs::~DataReductionProxyStatisticsPrefs() {
+  // This object is created on UI thread, but destroyed on IO thread. So no
+  // DCHECK on thread_checker_ here.
+}
+
+void DataReductionProxyStatisticsPrefs::ShutdownOnUIThread() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  WritePrefs();
   pref_change_registrar_->RemoveAll();
   weak_factory_.InvalidateWeakPtrs();
 }
@@ -73,7 +77,7 @@
   pref_change_registrar_->Init(pref_service_);
   pref_change_registrar_->Add(prefs::kUpdateDailyReceivedContentLengths,
       base::Bind(&DataReductionProxyStatisticsPrefs::OnUpdateContentLengths,
-                 GetWeakPtr()));
+                                         weak_factory_.GetWeakPtr()));
 }
 
 void DataReductionProxyStatisticsPrefs::OnUpdateContentLengths() {
@@ -151,7 +155,7 @@
   task_runner_->PostDelayedTask(
       FROM_HERE,
       base::Bind(&DataReductionProxyStatisticsPrefs::WritePrefs,
-                 GetWeakPtr()),
+                 weak_factory_.GetWeakPtr()),
                  delay_);
 
   delayed_task_posted_ = true;
@@ -182,9 +186,4 @@
   return value;
 }
 
-base::WeakPtr<DataReductionProxyStatisticsPrefs>
-DataReductionProxyStatisticsPrefs::GetWeakPtr() {
-  return weak_factory_.GetWeakPtr();
-}
-
 }  // namespace data_reduction_proxy