Rename UserId to UserHandle.

This is the start of turning this into a formal public API.

Change-Id: I5786d2c320f1de41a06ed5d0f65adb68967287a0
diff --git a/core/java/android/content/ContentProvider.java b/core/java/android/content/ContentProvider.java
index b22179e..8a69c3a 100644
--- a/core/java/android/content/ContentProvider.java
+++ b/core/java/android/content/ContentProvider.java
@@ -35,7 +35,7 @@
 import android.os.ParcelFileDescriptor;
 import android.os.Process;
 import android.os.RemoteException;
-import android.os.UserId;
+import android.os.UserHandle;
 import android.util.Log;
 
 import java.io.File;