NetworkProvider: add missing synchronization am: aecfab5f72

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2148673

Change-Id: I24349ba44e347d3359a3fd2c9f6a7cd84b0fb725
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>