Batch TabIdManagerTest

Speedup: 2783ms -> 36ms (99% speedup)

Bug: 1166919
Change-Id: If7b9e406fb5c1ce46e4a224542fe0ab60ee34c32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2631227
Commit-Queue: David Maunder <davidjm@chromium.org>
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844112}

chrome/android/java/src/org/chromium/chrome/browser/tab/TabIdManager.java

@@ -95,4 +95,9 @@ public class TabIdManager {
         mPreferences = SharedPreferencesManager.getInstance();
         mIdCounter.set(mPreferences.readInt(ChromePreferenceKeys.TAB_ID_MANAGER_NEXT_ID));
     }
+
+    @VisibleForTesting
+    static void resetInstanceForTesting() {
+        sInstance = null;
+    }
 }
\ No newline at end of file

chrome/android/javatests/src/org/chromium/chrome/browser/tab/TabIdManagerTest.java

@@ -16,18 +16,21 @@ import org.junit.runner.RunWith;
 
 import org.chromium.base.test.UiThreadTest;
 import org.chromium.base.test.util.AdvancedMockContext;
+import org.chromium.base.test.util.Batch;
 import org.chromium.chrome.browser.preferences.ChromePreferenceKeys;
 import org.chromium.chrome.browser.preferences.SharedPreferencesManager;
 import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 
 /** Tests for the TabIdManager. */
 @RunWith(ChromeJUnit4ClassRunner.class)
+@Batch(Batch.UNIT_TESTS)
 public class TabIdManagerTest {
     Context mContext;
 
     @Before
     public void setUp() {
         mContext = new AdvancedMockContext(InstrumentationRegistry.getTargetContext());
+        TabIdManager.resetInstanceForTesting();
     }
 
     /** Tests that IDs are stored and generated properly. */