Add a policy to always show the Cast toolbar icon

chrome/browser/profiles/profile_impl.cc

 // Copyright (c) 2012 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 "chrome/browser/profiles/profile_impl.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <utility>
@@ skipping 371 matching lines @@
                                home_page_flags);
 #if BUILDFLAG(ENABLE_PRINTING)
   registry->RegisterBooleanPref(prefs::kPrintingEnabled, true);
 #endif
   registry->RegisterBooleanPref(prefs::kPrintPreviewDisabled, false);
   registry->RegisterStringPref(
       prefs::kPrintPreviewDefaultDestinationSelectionRules, std::string());
   registry->RegisterBooleanPref(prefs::kForceEphemeralProfiles, false);
 #if defined(ENABLE_MEDIA_ROUTER)
   registry->RegisterBooleanPref(prefs::kEnableMediaRouter, true);
-#endif
+#if !defined(OS_ANDROID)
+  registry->RegisterBooleanPref(prefs::kShowCastIconInToolbar, false);
+#endif  // !defined(OS_ANDROID)
+#endif  // defined(ENABLE_MEDIA_ROUTER)
   // Initialize the cache prefs.
   registry->RegisterFilePathPref(prefs::kDiskCacheDir, base::FilePath());
   registry->RegisterIntegerPref(prefs::kDiskCacheSize, 0);
   registry->RegisterIntegerPref(prefs::kMediaCacheSize, 0);
 }
 
 ProfileImpl::ProfileImpl(
     const base::FilePath& path,
     Delegate* delegate,
     CreateMode create_mode,
@@ skipping 872 matching lines @@
 ProfileImpl::CreateDomainReliabilityMonitor(PrefService* local_state) {
   domain_reliability::DomainReliabilityService* service =
       domain_reliability::DomainReliabilityServiceFactory::GetInstance()->
           GetForBrowserContext(this);
   if (!service)
     return std::unique_ptr<domain_reliability::DomainReliabilityMonitor>();
 
   return service->CreateMonitor(
       BrowserThread::GetTaskRunnerForThread(BrowserThread::IO));
 }