Rename the binder call createActivityContainer

Change the call to createVirtualActivityContainer to better describe what's
actually being created with the call.

Change-Id: Id3a32df19a5bb6740cbabcd65897349e9f2f2946
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index a612575..3227efa 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -2546,7 +2546,7 @@
         return null;
     }
 
-    ActivityContainer createActivityContainer(ActivityRecord parentActivity,
+    ActivityContainer createVirtualActivityContainer(ActivityRecord parentActivity,
             IActivityContainerCallback callback) {
         ActivityContainer activityContainer =
                 new VirtualActivityContainer(parentActivity, callback);