Create the SystemUpdate activity class.

Test: tested sample app with sideloading.

Change-Id: I0d1661cea57c706b4981a4cda9f9b69fdeb69292
diff --git a/sample_updater/Android.mk b/sample_updater/Android.mk
index d6764bd..2b0fcbe 100644
--- a/sample_updater/Android.mk
+++ b/sample_updater/Android.mk
@@ -22,4 +22,6 @@
 LOCAL_SDK_VERSION := system_current
 LOCAL_MODULE_TAGS := optional
 
+LOCAL_SRC_FILES := $(call all-java-files-under, src)
+
 include $(BUILD_PACKAGE)