Allow the cast tray to function as expected when the installed extension is missing API methods.

chrome/browser/ui/ash/cast_config_delegate_chromeos.cc

Index: chrome/browser/ui/ash/cast_config_delegate_chromeos.cc
diff --git a/chrome/browser/ui/ash/cast_config_delegate_chromeos.cc b/chrome/browser/ui/ash/cast_config_delegate_chromeos.cc
index 3f0b87bf5b0e8c360b6715cb9009a6aa0535477c..9873cf404c009dd69fa9d0d8da2cd80f6a693ae2 100644
--- a/chrome/browser/ui/ash/cast_config_delegate_chromeos.cc
+++ b/chrome/browser/ui/ash/cast_config_delegate_chromeos.cc
@@ -138,8 +138,14 @@ void CastConfigDelegateChromeos::CastToReceiver(
                     "');");
 }
 
-void CastConfigDelegateChromeos::StopCasting(const std::string& activity_id) {
+void CastConfigDelegateChromeos::StopCasting() {
   ExecuteJavaScript("backgroundSetup.stopCastMirroring('user-stop');");
+
+  // TODO(jdufault): Remove this after stopCastMirroring is properly exported.
+  // The current beta/release versions of the cast extension do not export
+  // stopCastMirroring, so we will also try to call the minified version.
+  // See crbug.com/489929.
+  ExecuteJavaScript("backgroundSetup.Qu('user-stop');");
 }
 
 void CastConfigDelegateChromeos::LaunchCastOptions() {