Hide XML adapter sample, since the APIs are now gone.

Also tweak API demos to use the new pretty background.

Change-Id: Idbb523880fff81f6e0f3ca241e4bdaa1dbc2f8f2
diff --git a/samples/XmlAdapters/Android.mk b/samples/XmlAdapters/Android.mk
index 24a3327..3224bbe 100644
--- a/samples/XmlAdapters/Android.mk
+++ b/samples/XmlAdapters/Android.mk
@@ -10,7 +10,8 @@
 
 LOCAL_PROGUARD_ENABLED := disabled
 
-include $(BUILD_PACKAGE)
+# XXX These APIs are not yet available in the platform.
+#include $(BUILD_PACKAGE)
 
 # Use the following include to make our test apk.
-include $(call all-makefiles-under,$(LOCAL_PATH))
+#include $(call all-makefiles-under,$(LOCAL_PATH))