Fix error prone build of WM tests in FrameworksServicesTests

An erroprone build is usually triggered by Presubmit-Ready and built by
TreeHugger. You may see some failures in Presubmit Build Status of the
Gerrit. The error messages contains nice explanations and the links to how
to fix these.

Bug: 113800711
Test: Trigger Presubmit-Ready in TreeHugger and see errorprone build
  successfully.
Test: Pass all WM presubmit tests in FrameworksServicesTests and WmTests
  $ tradefed.sh run commandAndExit FrameworksServicesTests \
      --include-filter com.android.server.wm. \
      --include-annotation android.platform.test.annotations.Presubmit \
      --exclude-annotation androidx.test.filters.FlakyTest
  $ tradefed.sh run commandAndExit WmTests \
      --include-filter com.android.server.wm. \
      --include-annotation android.platform.test.annotations.Presubmit \
      --exclude-annotation androidx.test.filters.FlakyTest
Change-Id: I06c8162d4196346c4e90557e75f29088f5917284
diff --git a/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java b/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java
index 0e9a63c..f01e9f0 100644
--- a/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java
+++ b/services/tests/servicestests/src/com/android/server/wm/TaskStackContainersTests.java
@@ -11,7 +11,7 @@
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
- * limitations under the License
+ * limitations under the License.
  */
 
 package com.android.server.wm;
@@ -27,17 +27,17 @@
 
 import android.platform.test.annotations.Presubmit;
 
+import androidx.test.filters.SmallTest;
+
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
-import androidx.test.filters.SmallTest;
-
 /**
  * Tests for the {@link DisplayContent.TaskStackContainers} container in {@link DisplayContent}.
  *
  * Build/Install/Run:
- *  atest FrameworksServicesTests:com.android.server.wm.TaskStackContainersTests
+ *  atest FrameworksServicesTests:TaskStackContainersTests
  */
 @SmallTest
 @Presubmit
@@ -45,11 +45,8 @@
 
     private TaskStack mPinnedStack;
 
-    @Override
     @Before
     public void setUp() throws Exception {
-        super.setUp();
-
         mPinnedStack = createStackControllerOnStackOnDisplay(
                 WINDOWING_MODE_PINNED, ACTIVITY_TYPE_STANDARD, mDisplayContent).mContainer;
         // Stack should contain visible app window to be considered visible.
@@ -61,12 +58,9 @@
         assertTrue(mPinnedStack.isVisible());
     }
 
-    @Override
     @After
     public void tearDown() throws Exception {
         mPinnedStack.removeImmediately();
-
-        super.tearDown();
     }
 
     @Test
@@ -121,14 +115,14 @@
         final Task task = createTaskInStack(stack, 0 /* userId */);
 
         // Add another display at top.
-        sWm.mRoot.positionChildAt(WindowContainer.POSITION_TOP, createNewDisplay(),
+        mWm.mRoot.positionChildAt(WindowContainer.POSITION_TOP, createNewDisplay(),
                 false /* includingParents */);
 
         // Move the task of {@code mDisplayContent} to top.
         stack.positionChildAt(WindowContainer.POSITION_TOP, task, true /* includingParents */);
-        final int indexOfDisplayWithPinnedStack = sWm.mRoot.mChildren.indexOf(mDisplayContent);
+        final int indexOfDisplayWithPinnedStack = mWm.mRoot.mChildren.indexOf(mDisplayContent);
 
         assertEquals("The testing DisplayContent should be moved to top with task",
-                sWm.mRoot.getChildCount() - 1, indexOfDisplayWithPinnedStack);
+                mWm.mRoot.getChildCount() - 1, indexOfDisplayWithPinnedStack);
     }
 }