In startActivityAsCaller, changing the way we get the userId.

BUG: 17170098

Change-Id: Ie7fbd547b664a9982895b77da1fbb28df139ce52
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index b1d84f5..2ec8a05 100755
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -3481,7 +3481,8 @@
         try {
             int ret = mStackSupervisor.startActivityMayWait(null, targetUid, targetPackage, intent,
                     resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
-                    null, null, null, null, options, UserHandle.getUserId(targetUid), null);
+                    null, null, null, null, options, UserHandle.getUserId(sourceRecord.app.uid),
+                    null);
             return ret;
         } catch (SecurityException e) {
             // XXX need to figure out how to propagate to original app.