Add a resource for demo mode launcher component name.

Bug: 29359781
Change-Id: I3fa56e21bba1643cfce79d92d562cf2a51e1ff66
diff --git a/core/res/res/values/config.xml b/core/res/res/values/config.xml
index 5fd3c36..6b4fb29 100644
--- a/core/res/res/values/config.xml
+++ b/core/res/res/values/config.xml
@@ -2487,7 +2487,7 @@
     </string-array>
 
     <!-- Component that is the default launcher when demo mode is enabled. -->
-    <string name="config_demoModeLauncherComponent"></string>
+    <string name="config_demoModeLauncherComponent">com.android.retaildemo/.DemoPlayer</string>
 
     <!-- Flag indicating whether round icons should be parsed from the application manifest. -->
     <bool name="config_useRoundIcon">false</bool>