Fix NPE in ActivityManagerService

Bug: 10294281
Change-Id: Iaf608ae099b90fac8ad726285652b5c3e74e1632
diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index a6d7e3c..be6119d 100644
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -8062,12 +8062,10 @@
             if (activity == null) {
                 Slog.w(TAG, "getAssistContextExtras error: no resumed activity");
                 validActivity = false;
-            }
-            if (activity.app == null || activity.app.thread == null) {
+            } else if (activity.app == null || activity.app.thread == null) {
                 Slog.w(TAG, "getAssistContextExtras error: no process for " + activity);
                 validActivity = false;
-            }
-            if (activity.app.pid == Binder.getCallingPid()) {
+            } else if (activity.app.pid == Binder.getCallingPid()) {
                 Slog.w(TAG, "getAssistContextExtras error: request process same as " + activity);
                 validActivity = false;
             }