Remove deprecated-declarations warnings.

ios/third_party/material_components_ios/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/locales.gni")
 
 config("config") {
   visibility = [ ":material_components_ios" ]
   include_dirs = [
     "src/components/AppBar/src",
     "src/components/ActivityIndicator/src",
     "src/components/ButtonBar/src",
     "src/components/Buttons/src",
     "src/components/CollectionCells/src",
     "src/components/CollectionLayoutAttributes/src",
     "src/components/Collections/src",
     "src/components/Dialogs/src",
     "src/components/FlexibleHeader/src",
     "src/components/HeaderStackView/src",
     "src/components/Ink/src",
     "src/components/NavigationBar/src",
     "src/components/OverlayWindow/src",
     "src/components/Palettes/src",
     "src/components/ProgressView/src",
     "src/components/ShadowElevations/src",
     "src/components/ShadowLayer/src",
     "src/components/Snackbar/src",
     "src/components/Typography/src",
   ]
-
-  cflags_objc = [
-    # Do not consider use of deprecated API as errors when building third-party
-    # libraries.
-    "-Wno-error=deprecated-declarations",
-  ]
 }
 
 _icon_names = [
   "ic_check",
   "ic_check_circle",
   "ic_chevron_right",
   "ic_info",
   "ic_radio_button_unchecked",
   "ic_reorder",
 ]
@@ skipping 319 matching lines @@
     ]
   }
 }
 
 foreach(icon_name, _icon_names) {
   material_component_icon_bundle("material_component_${icon_name}_bundle") {
     visibility = [ ":material_components_ios" ]
     icon_name = "$icon_name"
   }
 }