Disable protected content button in Guest mode settings

chrome/browser/ui/webui/options/content_settings_handler.cc

Index: chrome/browser/ui/webui/options/content_settings_handler.cc
diff --git a/chrome/browser/ui/webui/options/content_settings_handler.cc b/chrome/browser/ui/webui/options/content_settings_handler.cc
index 48865b87f76380e62c5a33669d3cd4353796d002..7a4babbba338d37453bf482a6ef61ca4d5a0a1ab 100644
--- a/chrome/browser/ui/webui/options/content_settings_handler.cc
+++ b/chrome/browser/ui/webui/options/content_settings_handler.cc
@@ -1495,8 +1495,14 @@ void ContentSettingsHandler::UpdateFlashMediaLinksVisibility() {
 }
 
 void ContentSettingsHandler::UpdateProtectedContentExceptionsButton() {
-  PrefService* prefs = user_prefs::UserPrefs::Get(GetBrowserContext(web_ui()));
+#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()));
   bool enable_exceptions = prefs->GetBoolean(prefs::kEnableDRM);
   web_ui()->CallJavascriptFunction(
       "ContentSettings.enableProtectedContentExceptions",