Waiting for launcher to start in workTabExists()

Change-Id: I08c5385b188dda81ee0dfc1bfd639a0892bd6584
diff --git a/tests/src/com/android/launcher3/ui/WorkTabTest.java b/tests/src/com/android/launcher3/ui/WorkTabTest.java
index 79c2d07..d9edc35 100644
--- a/tests/src/com/android/launcher3/ui/WorkTabTest.java
+++ b/tests/src/com/android/launcher3/ui/WorkTabTest.java
@@ -54,7 +54,7 @@
     @Test
     public void workTabExists() {
         mDevice.pressHome();
-
+        waitForLauncherCondition("Launcher didn't start", launcher -> launcher != null);
         executeOnLauncher(launcher -> launcher.getStateManager().goToState(ALL_APPS));
 
         /*