Remove IS_IOS checks in chrome/

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index c825b79c8501e32ae599df274bb23bfd894811ae..9b21c1c16e1278c6794ec75b9ed5c793a8e7d092 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1012,7 +1012,7 @@ const char kSavingBrowserHistoryDisabled[] = "history.saving_disabled";
 // permitted.
 const char kAllowDeletingBrowserHistory[] = "history.deleting_enabled";
 
-#if !defined(OS_ANDROID) && !defined(OS_IOS)
+#if !defined(OS_ANDROID)
 // Whether the "Click here to clear your browsing data" tooltip promo has been
 // shown on the Material Design History page.
 const char kMdHistoryMenuPromoShown[] = "history.menu_promo_shown";