Adds methods for Cast support to ios::ChromeBrowserProvider.

ios/public/provider/chrome/browser/chrome_browser_provider.mm

 // Copyright 2013 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.
 
 #include "ios/public/provider/chrome/browser/chrome_browser_provider.h"
 
 #include <cstddef>
 
 #include "base/logging.h"
 #include "components/metrics/metrics_provider.h"
@@ skipping 88 matching lines @@
 
 UITextField<TextFieldStyling>* ChromeBrowserProvider::CreateStyledTextField(
     CGRect frame) const {
   return nil;
 }
 
 id<AppRatingPrompt> ChromeBrowserProvider::CreateAppRatingPrompt() const {
   return nil;
 }
 
+void ChromeBrowserProvider::InitializeCastService(id main_tab_model) const {}
+
+void ChromeBrowserProvider::AttachTabHelpers(web::WebState* web_state,
+                                             id tab) const {}
+
 bool ChromeBrowserProvider::IsSafeBrowsingEnabled(
     const base::Closure& on_update_callback) {
   return false;
 }
 
 std::unique_ptr<sync_sessions::SyncedWindowDelegatesGetter>
 ChromeBrowserProvider::CreateSyncedWindowDelegatesGetter(
     ios::ChromeBrowserState* browser_state) {
   return nullptr;
 }
 
 }  // namespace ios