From f470e292d858cd1bbd688d7398beb2dabd2622ac Mon Sep 17 00:00:00 2001
From: Kathy Chen <kxchen@google.com>
Date: Mon, 8 May 2023 22:59:05 +0000
Subject: [PATCH] Revert "[AC] Fix NPE. If the client sends multiple unregister
 requests at the same time, the client request could be null before the next
 request is processed."

This reverts commit 21b89197a982c6dc63f0bcc0d9ccfc8cad4828ac.

Reason for revert: Need to address WARNING reported by Error Prone: [SynchronizeOnNonFinalField] Synchronizing on non-final fields is not safe: if the field is ever updated, different threads may end up locking on different objects.

Change-Id: I97acc0c933795e90e9e7fa0e72798259acf862dc
---
 .../server/ambientcontext/AmbientContextManagerService.java   | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/ambientcontext/AmbientContextManagerService.java b/services/core/java/com/android/server/ambientcontext/AmbientContextManagerService.java
index 9e23363680eaa..46e60014b851a 100644
--- a/services/core/java/com/android/server/ambientcontext/AmbientContextManagerService.java
+++ b/services/core/java/com/android/server/ambientcontext/AmbientContextManagerService.java
@@ -56,11 +56,11 @@ import java.io.FileDescriptor;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * System service for managing {@link AmbientContextEvent}s.
@@ -600,7 +600,7 @@ public class AmbientContextManagerService extends
             unregisterObserver_enforcePermission();
             assertCalledByPackageOwner(callingPackage);
 
-            synchronized (mExistingClientRequests) {
+            synchronized (mLock) {
                 for (ClientRequest cr : mExistingClientRequests) {
                     if (cr.getPackageName().equals(callingPackage)) {
                         AmbientContextManagerPerUserService service =