Disable protected content button in Guest mode settings

chrome/browser/ui/webui/options/content_settings_handler.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/ui/webui/options/content_settings_handler.h"
 
 #include <algorithm>
 #include <map>
 #include <vector>
 
@@ skipping 1477 matching lines @@
             media_settings_.flash_default_setting,
             media_settings_.flash_exceptions,
             media_settings_.policy_disable_audio,
             media_settings_.policy_disable_video)) {
       ShowFlashMediaLink(EXCEPTIONS, true);
     }
   }
 }
 
 void ContentSettingsHandler::UpdateProtectedContentExceptionsButton() {
+#if defined(OS_CHROMEOS)
+  // Guests cannot modify exceptions. UIAccountTweaks will disabled the button.
+  if (user_manager::UserManager::Get()->IsLoggedInAsGuest())
+    return;
+#endif
+
+  // Exceptions apply only when the feature is enabled.
   PrefService* prefs = user_prefs::UserPrefs::Get(GetBrowserContext(web_ui()));
-  // Exceptions apply only when the feature is enabled.
   bool enable_exceptions = prefs->GetBoolean(prefs::kEnableDRM);
   web_ui()->CallJavascriptFunction(
       "ContentSettings.enableProtectedContentExceptions",
       base::FundamentalValue(enable_exceptions));
 }
 
 }  // namespace options