Add tilegroups as batched tests.

This reduces test execution time from about 14756ms to 6030ms

Bug: 989569
Change-Id: Ib7e83e97f4a9814ba964d455d82a40857d698e16
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429253Reviewed-by: Cathy Li <chili@chromium.org>
Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Commit-Queue: benjamin joyce <bjoyce@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810878}

chrome/android/javatests/src/org/chromium/chrome/browser/suggestions/tile/TileGroupTest.java

@@ -20,6 +20,7 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import org.chromium.base.test.util.Batch;
 import org.chromium.base.test.util.CallbackHelper;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.Feature;
@@ -57,6 +58,7 @@ import java.util.concurrent.TimeoutException;
  * Instrumentation tests for {@link TileGroup} on the New Tab Page.
  */
 @RunWith(ChromeJUnit4ClassRunner.class)
+@Batch(Batch.PER_CLASS)
 @CommandLineFlags.Add({ChromeSwitches.DISABLE_FIRST_RUN_EXPERIENCE})
 public class TileGroupTest {
     @Rule