Not treating "Screen is empty" as an anomaly in NavigationModeSwitchRule

It's an acceptable state when Launcher just starts under
 instrumentation.

Change-Id: Ia6eb2550effbd9236bb955e0c0e04416fc5fa506
diff --git a/quickstep/tests/src/com/android/quickstep/NavigationModeSwitchRule.java b/quickstep/tests/src/com/android/quickstep/NavigationModeSwitchRule.java
index 5158939..fa4c7b9 100644
--- a/quickstep/tests/src/com/android/quickstep/NavigationModeSwitchRule.java
+++ b/quickstep/tests/src/com/android/quickstep/NavigationModeSwitchRule.java
@@ -30,6 +30,7 @@
 import android.content.pm.PackageManager;
 import android.util.Log;
 
+import androidx.test.uiautomator.By;
 import androidx.test.uiautomator.UiDevice;
 
 import com.android.launcher3.tapl.LauncherInstrumentation;
@@ -80,7 +81,12 @@
             Mode mode = description.getAnnotation(NavigationModeSwitch.class).mode();
             return new Statement() {
                 private void assertTrue(String message, boolean condition) {
-                    mLauncher.checkForAnomaly();
+                    if (mLauncher.getDevice().hasObject(By.textStartsWith(""))) {
+                        // The condition above is "screen is not empty". We are not treating
+                        // "Screen is empty" as an anomaly here. It's an acceptable state when
+                        // Launcher just starts under instrumentation.
+                        mLauncher.checkForAnomaly();
+                    }
                     if (!condition) {
                         final AssertionError assertionError = new AssertionError(message);
                         FailureWatcher.onError(mLauncher.getDevice(), description, assertionError);