This Android App works with the Google Cloud Messaging service and the mock server defined in ../GcmMockServer. You really need to read the Android Cookbook recipe at https://androidcookbook.com/Recipe.seam?recipeId=4601 to figure out all the moving pieces!
Also note that you MUST import the google-play-services_lib project from $ANDROID_SDK/extras/google/google_play_services/libproject/ in order for the client to compile (and do check "Copy projects into workspace" to cope with updates!). See the Android Cookbook article for how to refer to it properly.