[Android][Signin] Enable disabled signin helper test

This CL enables the disabled signin helper test.

Bug: 577880
Change-Id: I14d5f818a1b091b6392dca8083c217e179993239
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1942089Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Commit-Queue: Alice Wang <aliceywang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720903}

chrome/android/javatests/src/org/chromium/chrome/browser/signin/SigninHelperTest.java

@@ -14,7 +14,6 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.RetryOnFailure;
 import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 import org.chromium.chrome.test.util.browser.signin.MockChangeEventChecker;
@@ -84,13 +83,12 @@ public class SigninHelperTest {
     }
 
     @Test
-    @DisabledTest(message = "crbug.com/568623")
     @SmallTest
     public void testNotSignedInAccountRename() {
         setSignedInAccountName("A");
         mEventChecker.insertRenameEvent("B", "C");
         SigninHelper.updateAccountRenameData(mEventChecker);
-        Assert.assertEquals(null, getNewSignedInAccountName());
+        Assert.assertNull(getNewSignedInAccountName());
     }
 
     @Test
@@ -113,7 +111,7 @@ public class SigninHelperTest {
         mEventChecker.insertRenameEvent("B", "C");
         mEventChecker.insertRenameEvent("C", "D");
         SigninHelper.updateAccountRenameData(mEventChecker);
-        Assert.assertEquals(null, getNewSignedInAccountName());
+        Assert.assertNull(getNewSignedInAccountName());
     }
 
     @Test
@@ -152,10 +150,6 @@ public class SigninHelperTest {
         ChromeSigninController.get().setSignedInAccountName(account);
     }
 
-    private String getSignedInAccountName() {
-        return ChromeSigninController.get().getSignedInAccountName();
-    }
-
     private String getNewSignedInAccountName() {
         return SigninHelper.getNewSignedInAccountName();
     }

chrome/test/android/javatests/src/org/chromium/chrome/test/util/browser/signin/MockChangeEventChecker.java

@@ -18,8 +18,7 @@ import java.util.Map;
  */
 public final class MockChangeEventChecker
         implements SigninHelper.AccountChangeEventChecker {
-    private Map<String, List<String>> mEvents =
-            new HashMap<String, List<String>>();
+    private Map<String, List<String>> mEvents = new HashMap<>();
 
     @Override
     public List<String> getAccountChangeEvents(
@@ -36,7 +35,7 @@ public final class MockChangeEventChecker
     private List<String> getEventList(String account) {
         List<String> eventsList = mEvents.get(account);
         if (eventsList == null) {
-            eventsList = new ArrayList<String>();
+            eventsList = new ArrayList<>();
             mEvents.put(account, eventsList);
         }
         return eventsList;