Define a new policy to disable clearing the browsing history from the UI.

chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc

Index: chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc
diff --git a/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc b/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc
index b03fb3741eccc243c8f510eadc88854673cd8b27..a2e2b3ab706bcfdf3b66f3f0d243970f945de2df 100644
--- a/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc
+++ b/chrome/browser/ui/webui/settings/settings_clear_browsing_data_handler.cc
@@ -100,13 +100,6 @@ void ClearBrowsingDataHandler::RegisterMessages() {
 }
 
 void ClearBrowsingDataHandler::OnJavascriptAllowed() {
-  PrefService* prefs = profile_->GetPrefs();
-  profile_pref_registrar_.Init(prefs);
-  profile_pref_registrar_.Add(
-      prefs::kAllowDeletingBrowserHistory,
-      base::Bind(&ClearBrowsingDataHandler::OnBrowsingHistoryPrefChanged,
-                 base::Unretained(this)));
-
   if (sync_service_)
     sync_service_observer_.Add(sync_service_);
 
@@ -118,7 +111,6 @@ void ClearBrowsingDataHandler::OnJavascriptAllowed() {
 }
 
 void ClearBrowsingDataHandler::OnJavascriptDisallowed() {
-  profile_pref_registrar_.RemoveAll();
   sync_service_observer_.RemoveAll();
   task_observer_.reset();
   counters_.clear();
@@ -252,15 +244,6 @@ void ClearBrowsingDataHandler::OnClearingTaskFinished(
   task_observer_.reset();
 }
 
-void ClearBrowsingDataHandler::OnBrowsingHistoryPrefChanged() {
-  CallJavascriptFunction(
-      "cr.webUIListenerCallback",
-      base::StringValue("browsing-history-pref-changed"),
-      base::FundamentalValue(
-          profile_->GetPrefs()->GetBoolean(
-              prefs::kAllowDeletingBrowserHistory)));
-}
-
 void ClearBrowsingDataHandler::HandleInitialize(const base::ListValue* args) {
   AllowJavascript();
   const base::Value* callback_id;