Merge "Fix NPE in BootReceiver" into main

        mHandler = thread.getThreadHandler();

        mWatcher = new TombstoneWatcher();

        mWatcher.startWatching();

    }

    void onSystemReady() {

        registerForUserRemoval();

        registerForPackageRemoval();

        // TombstoneWatcher depends on DropboxManagerService.

        // DropboxManagerService started before systemReady.

        // So it is good to call startWatching here.

        mWatcher.startWatching();

        BootReceiver.initDropboxRateLimiter();