Remove dependency on hidden NetworkStats API

GB_IN_BYTES is not API in TrafficStats; remove the API usage and just
use a constant in the test.

Bug: 197717846
Test: atest DownloadProviderTests
  (cherry-picked from ag/16780144)
Change-Id: I0afaa4788fe18a75972473a72fdfe071798b1011
Merged-In: I0afaa4788fe18a75972473a72fdfe071798b1011
diff --git a/tests/src/com/android/providers/downloads/PublicApiFunctionalTest.java b/tests/src/com/android/providers/downloads/PublicApiFunctionalTest.java
index f45e102..d36635a 100644
--- a/tests/src/com/android/providers/downloads/PublicApiFunctionalTest.java
+++ b/tests/src/com/android/providers/downloads/PublicApiFunctionalTest.java
@@ -18,7 +18,6 @@
 
 import static android.app.DownloadManager.STATUS_FAILED;
 import static android.app.DownloadManager.STATUS_PAUSED;
-import static android.net.TrafficStats.GB_IN_BYTES;
 import static android.text.format.DateUtils.SECOND_IN_MILLIS;
 
 import static org.mockito.Matchers.anyInt;
@@ -71,6 +70,7 @@
 public class PublicApiFunctionalTest extends AbstractPublicApiTest {
     private static final String REDIRECTED_PATH = "/other_path";
     private static final String ETAG = "my_etag";
+    private static final long GB_IN_BYTES = 1024 * 1024 * 1024;
 
     protected File mTestDirectory;
     private NotificationManager mNotifManager;