Expose way to enable/disable translate.

ios/web_view/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/ios/ios_sdk.gni")
 import("//build/config/ios/rules.gni")
 import("//components/grpc_support/include/headers.gni")
 import("//ios/build/config.gni")
 import("//testing/test.gni")
 import("//tools/grit/repack.gni")
 
 config("config") {
   defines = [ "CWV_IMPLEMENTATION" ]
   libs = [
     "CoreGraphics.framework",
     "Foundation.framework",
     "MobileCoreServices.framework",
     "UIKit.framework",
   ]
 }
 
 # These variables are used to share framework sources with both ChromeWebView
 # and CrNetChromeWebView frameworks.
 ios_web_view_public_headers = [
   "public/ChromeWebView.h",
   "public/cwv_export.h",
   "public/cwv_html_element.h",
   "public/cwv_navigation_action.h",
   "public/cwv_navigation_delegate.h",
+  "public/cwv_preferences.h",
   "public/cwv_scroll_view.h",
   "public/cwv_scroll_view_delegate.h",
   "public/cwv_translation_controller.h",
   "public/cwv_translation_controller_delegate.h",
   "public/cwv_translation_language.h",
   "public/cwv_translation_policy.h",
   "public/cwv_ui_delegate.h",
   "public/cwv_user_content_controller.h",
   "public/cwv_user_script.h",
   "public/cwv_web_view.h",
   "public/cwv_web_view_configuration.h",
 ]
 
 ios_web_view_sources = [
   "internal/app/application_context.cc",
   "internal/app/application_context.h",
   "internal/app/web_view_io_thread.h",
   "internal/app/web_view_io_thread.mm",
   "internal/cwv_html_element.mm",
   "internal/cwv_html_element_internal.h",
   "internal/cwv_navigation_action.mm",
   "internal/cwv_navigation_action_internal.h",
+  "internal/cwv_preferences.mm",
+  "internal/cwv_preferences_internal.h",
   "internal/cwv_scroll_view.mm",
   "internal/cwv_scroll_view_internal.h",
   "internal/cwv_user_content_controller.mm",
   "internal/cwv_user_content_controller_internal.h",
   "internal/cwv_user_script.mm",
   "internal/cwv_web_view.mm",
   "internal/cwv_web_view_configuration.mm",
   "internal/cwv_web_view_configuration_internal.h",
   "internal/pref_names.cc",
   "internal/pref_names.h",
@@ skipping 230 matching lines @@
   }
 
   group("cronet_ios_web_view_package") {
     deps = [
       ":cronet_ios_web_view_dsym_archive",
       ":cronet_ios_web_view_generate_license",
       ":cronet_ios_web_view_package_copy",
     ]
   }
 }