Fix a bug where a NetworkAgent gets repeatedly torn down

mUids is not marshalled correctly when null so if the
NetworkAgent runs in another process and is not a VPN then
the system will see its allowed Uids as being the empty
list (= nobody can use this network) instead of a null
list (= everybody can use this network). This breaks
emulator networking.

Bug: 72436966
Test: runtests frameworks-net
Test: also manual testing, this does fix emulator networking
      and seems not to break phone networking
Cherry-pick of : Id2bbf3808e80b19cd055c832c11cf72372710942

Change-Id: I4b88d5eccbdea745a947d12635cd751e38632589

core/java/android/net/NetworkCapabilities.java

@@ -892,7 +892,7 @@ public final class NetworkCapabilities implements Parcelable {
      *
      * @hide
      */
-    private Set<UidRange> mUids = null;
+    private ArraySet<UidRange> mUids = null;
 
     /**
      * Convenience method to set the UIDs this network applies to to a single UID.
@@ -1178,7 +1178,7 @@ public final class NetworkCapabilities implements Parcelable {
         dest.writeInt(mLinkDownBandwidthKbps);
         dest.writeParcelable((Parcelable) mNetworkSpecifier, flags);
         dest.writeInt(mSignalStrength);
-        dest.writeArraySet(new ArraySet<>(mUids));
+        dest.writeArraySet(mUids);
     }
 
     public static final Creator<NetworkCapabilities> CREATOR =