Lock access to managed services.

Fixes: 35873807
Test: manual, set a notification to enqueue once a second for a few
minutes while also repeatedly granting and denying notification listener
access to a couple of apps in Settings and verifying
that nothing crashes and log is clean.

Change-Id: I15f429d61bf5f9ad639e524a94288a6d2db2cb56
diff --git a/services/core/java/com/android/server/notification/ManagedServices.java b/services/core/java/com/android/server/notification/ManagedServices.java
index 000cf2e..90e9b92 100644
--- a/services/core/java/com/android/server/notification/ManagedServices.java
+++ b/services/core/java/com/android/server/notification/ManagedServices.java
@@ -90,7 +90,7 @@
 
     // contains connections to all connected services, including app services
     // and system services
-    protected final ArrayList<ManagedServiceInfo> mServices = new ArrayList<ManagedServiceInfo>();
+    private final ArrayList<ManagedServiceInfo> mServices = new ArrayList<ManagedServiceInfo>();
     // things that will be put into mServices as soon as they're ready
     private final ArrayList<String> mServicesBinding = new ArrayList<String>();
     // lists the component names of all enabled (and therefore potentially connected)