Remove usage of Math.randomLongInternal

As a part of internal libcore API cleanup some of the functions
previously exposed are getting removed from public surface.
Math#randomLongInternal is a wrapper around java.util.Random and has no
specific implications so its usages are get refactored.

Bug: 154796679
Test: m droid
Merged-In: I019000d2b35c256e7c8a251a95bd9384d3503335
Change-Id: I019000d2b35c256e7c8a251a95bd9384d3503335

services/tests/servicestests/src/com/android/server/usage/AppStandbyControllerTests.java

@@ -114,6 +114,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -166,6 +167,8 @@ public class AppStandbyControllerTests {
     /** Mock variable used in {@link MyInjector#isPackageInstalled(String, int, int)} */
     private static boolean isPackageInstalled = true;
 
+    private static final Random sRandom = new Random();
+
     private MyInjector mInjector;
     private AppStandbyController mController;
 
@@ -294,7 +297,7 @@ public class AppStandbyControllerTests {
 
         @Override
         File getDataSystemDirectory() {
-            return new File(getContext().getFilesDir(), Long.toString(Math.randomLongInternal()));
+            return new File(getContext().getFilesDir(), Long.toString(sRandom.nextLong()));
         }
 
         @Override