diff --git a/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java b/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java
index dea9294ff75be..bce1320f1d7ef 100644
--- a/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java
+++ b/services/tests/wmtests/src/com/android/server/wm/SystemServicesTestRule.java
@@ -335,7 +335,11 @@ public class SystemServicesTestRule implements TestRule {
         mWmService.mConstants.dispose();
         mWmService.mHighRefreshRateBlacklist.dispose();
 
+        // This makes sure the posted messages without delay are processed, e.g.
+        // DisplayPolicy#release, WindowManagerService#setAnimationScale.
         waitUntilWindowManagerHandlersIdle();
+        // Clear all posted messages with delay, so they don't be executed at unexpected times.
+        cleanupWindowManagerHandlers();
         // Needs to explicitly dispose current static threads because there could be messages
         // scheduled at a later time, and all mocks are invalid when it's executed.
         DisplayThread.dispose();
@@ -399,8 +403,6 @@ public class SystemServicesTestRule implements TestRule {
         if (wm == null) {
             return;
         }
-        // Removing delayed FORCE_GC message decreases time for waiting idle.
-        wm.mH.removeMessages(WindowManagerService.H.FORCE_GC);
         waitHandlerIdle(wm.mH);
         waitHandlerIdle(wm.mAnimationHandler);
         // This is a different handler object than the wm.mAnimationHandler above.
@@ -408,25 +410,8 @@ public class SystemServicesTestRule implements TestRule {
         waitHandlerIdle(SurfaceAnimationThread.getHandler());
     }
 
-    private void waitHandlerIdle(Handler handler) {
-        synchronized (mCurrentMessagesProcessed) {
-            // Add a message to the handler queue and make sure it is fully processed before we move
-            // on. This makes sure all previous messages in the handler are fully processed vs. just
-            // popping them from the message queue.
-            mCurrentMessagesProcessed.set(false);
-            handler.post(() -> {
-                synchronized (mCurrentMessagesProcessed) {
-                    mCurrentMessagesProcessed.set(true);
-                    mCurrentMessagesProcessed.notifyAll();
-                }
-            });
-            while (!mCurrentMessagesProcessed.get()) {
-                try {
-                    mCurrentMessagesProcessed.wait();
-                } catch (InterruptedException e) {
-                }
-            }
-        }
+    static void waitHandlerIdle(Handler handler) {
+        handler.runWithScissors(() -> { }, 0 /* timeout */);
     }
 
     void waitUntilWindowAnimatorIdle() {
diff --git a/services/tests/wmtests/src/com/android/server/wm/WindowTestsBase.java b/services/tests/wmtests/src/com/android/server/wm/WindowTestsBase.java
index 6a64d1c976c46..94c204ab0fe05 100644
--- a/services/tests/wmtests/src/com/android/server/wm/WindowTestsBase.java
+++ b/services/tests/wmtests/src/com/android/server/wm/WindowTestsBase.java
@@ -52,13 +52,9 @@ import android.view.WindowManager;
 
 import com.android.server.AttributeCache;
 
-import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
 
-import java.util.HashSet;
-import java.util.LinkedList;
-
 /**
  * Common base class for window manager unit test classes.
  *
@@ -85,7 +81,6 @@ class WindowTestsBase extends SystemServiceTestsBase {
     WindowState mAppWindow;
     WindowState mChildAppWindowAbove;
     WindowState mChildAppWindowBelow;
-    HashSet<WindowState> mCommonWindows;
 
     /**
      * Spied {@link Transaction} class than can be used to verify calls.
@@ -115,7 +110,6 @@ class WindowTestsBase extends SystemServiceTestsBase {
             mDisplayContent = createNewDisplay(true /* supportIme */);
 
             // Set-up some common windows.
-            mCommonWindows = new HashSet<>();
             synchronized (mWm.mGlobalLock) {
                 mWallpaperWindow = createCommonWindow(null, TYPE_WALLPAPER, "wallpaperWindow");
                 mImeWindow = createCommonWindow(null, TYPE_INPUT_METHOD, "mImeWindow");
@@ -151,48 +145,9 @@ class WindowTestsBase extends SystemServiceTestsBase {
         // Called before display is created.
     }
 
-    @After
-    public void tearDownBase() {
-        // If @After throws an exception, the error isn't logged. This will make sure any failures
-        // in the tear down are clear. This can be removed when b/37850063 is fixed.
-        try {
-            // Test may schedule to perform surface placement or other messages. Wait until a
-            // stable state to clean up for consistency.
-            waitUntilHandlersIdle();
-
-            final LinkedList<WindowState> nonCommonWindows = new LinkedList<>();
-
-            synchronized (mWm.mGlobalLock) {
-                mWm.mRoot.forAllWindows(w -> {
-                    if (!mCommonWindows.contains(w)) {
-                        nonCommonWindows.addLast(w);
-                    }
-                }, true /* traverseTopToBottom */);
-
-                while (!nonCommonWindows.isEmpty()) {
-                    nonCommonWindows.pollLast().removeImmediately();
-                }
-
-                // Remove app transition & window freeze timeout callbacks to prevent unnecessary
-                // actions after test.
-                mWm.getDefaultDisplayContentLocked().mAppTransition
-                        .removeAppTransitionTimeoutCallbacks();
-                mWm.mH.removeMessages(WindowManagerService.H.WINDOW_FREEZE_TIMEOUT);
-                mDisplayContent.mInputMethodTarget = null;
-            }
-
-            // Cleaned up everything in Handler.
-            cleanupWindowManagerHandlers();
-        } catch (Exception e) {
-            Log.e(TAG, "Failed to tear down test", e);
-            throw e;
-        }
-    }
-
     private WindowState createCommonWindow(WindowState parent, int type, String name) {
         synchronized (mWm.mGlobalLock) {
             final WindowState win = createWindow(parent, type, name);
-            mCommonWindows.add(win);
             // Prevent common windows from been IMe targets
             win.mAttrs.flags |= FLAG_NOT_FOCUSABLE;
             return win;