Instead of a raw AIDL interface, give DropBox a Java
interface (android.os.DropBox); move the Binder interface
behind the scenes.  Make DropBoxEntry into DropBox.Entry.
Make it possible to get a dropbox from an (Application)Context
with the usual getSystemService(DROPBOX_SERVICE) type thing.
Update the tests accordingly.
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 1a7416a..5f30710 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -296,7 +296,7 @@
 
             try {
                 Log.i(TAG, "DropBox Service");
-                ServiceManager.addService("dropbox",
+                ServiceManager.addService(Context.DROPBOX_SERVICE,
                         new DropBoxService(context, new File("/data/system/dropbox")));
             } catch (Throwable e) {
                 Log.e(TAG, "Failure starting DropBox Service", e);