Multi-user - wallpaper service

- Allow each user to have their own wallpaper (live or static).
- Migrate old wallpaper on upgrade.
- Update SystemBackupAgent to backup/restore from primary user's
  new wallpaper directory.

Reduce dependency on Binder.getOrigCallingUser() by passing the
userId for bindService.

Change-Id: I19c8c3296d3d2efa7f28f951d4b84407489e2166
diff --git a/core/java/android/app/ContextImpl.java b/core/java/android/app/ContextImpl.java
index 37900b6..ebf692a 100644
--- a/core/java/android/app/ContextImpl.java
+++ b/core/java/android/app/ContextImpl.java
@@ -1125,6 +1125,12 @@
     @Override
     public boolean bindService(Intent service, ServiceConnection conn,
             int flags) {
+        return bindService(service, conn, flags, UserId.getUserId(Process.myUid()));
+    }
+
+    /** @hide */
+    @Override
+    public boolean bindService(Intent service, ServiceConnection conn, int flags, int userId) {
         IServiceConnection sd;
         if (mPackageInfo != null) {
             sd = mPackageInfo.getServiceDispatcher(conn, getOuterContext(),
@@ -1143,7 +1149,7 @@
             int res = ActivityManagerNative.getDefault().bindService(
                 mMainThread.getApplicationThread(), getActivityToken(),
                 service, service.resolveTypeIfNeeded(getContentResolver()),
-                sd, flags);
+                sd, flags, userId);
             if (res < 0) {
                 throw new SecurityException(
                         "Not allowed to bind to service " + service);