[Android][Test] Batch IncognitoInterstitialTest

This CL batches IncognitoInterstitialTest.

Bug: 1149978
Change-Id: I600053a52536dd06a0e34c854818889d830d18bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2546598Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Alice Wang <aliceywang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828743}

chrome/browser/incognito/interstitial/android/java/src/org/chromium/chrome/browser/incognito/interstitial/IncognitoInterstitialTest.java

@@ -27,6 +27,7 @@ import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+import org.chromium.base.test.util.Batch;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.flags.ChromeSwitches;
@@ -39,6 +40,7 @@ import org.chromium.ui.test.util.DummyUiActivity;
  */
 @RunWith(ChromeJUnit4ClassRunner.class)
 @CommandLineFlags.Add({ChromeSwitches.DISABLE_FIRST_RUN_EXPERIENCE})
+@Batch(Batch.PER_CLASS)
 public class IncognitoInterstitialTest {
     @Mock
     private IncognitoInterstitialDelegate mIncognitoInterstitialDelegateMock;