Merge "Remove hidden API usage from ProxyTracker"

import android.net.Uri;

import android.os.Binder;

import android.os.Handler;

import android.os.HandlerExecutor;

import android.os.UserHandle;

import android.provider.Settings;

import android.text.TextUtils;

        PacProxyInstalledListener listener = new PacProxyInstalledListener(pacChangedEvent);

        mPacProxyManager.addPacProxyInstalledListener(

                new HandlerExecutor(mConnectivityServiceHandler), listener);

                mConnectivityServiceHandler::post, listener);

    }

    // Convert empty ProxyInfo's to null as null-checks are used to determine if proxies are present