Bugfix, add extra wait when searching in app grid.

Bug: 141328109
Test: build and run test
Change-Id: I91d96b04c4329b5f2d6d30bef94f2c5287b5e8f3
(cherry picked from commit c113ce054525856092a77e67c22d154251418f40)
diff --git a/libraries/launcher-helper/src/android/support/test/launcherhelper/AutoLauncherStrategy.java b/libraries/launcher-helper/src/android/support/test/launcherhelper/AutoLauncherStrategy.java
index dcbe7e1..c547f0d 100644
--- a/libraries/launcher-helper/src/android/support/test/launcherhelper/AutoLauncherStrategy.java
+++ b/libraries/launcher-helper/src/android/support/test/launcherhelper/AutoLauncherStrategy.java
@@ -338,11 +338,11 @@
                 mDevice.waitForIdle();
             }
 
-            UiObject2 app = mDevice.findObject(appSelector);
+            UiObject2 app = mDevice.wait(Until.findObject(appSelector), UI_WAIT_TIMEOUT);
             while (app == null && down.isEnabled()) {
                 down.click();
                 mDevice.waitForIdle();
-                app = mDevice.findObject(appSelector);
+                app = mDevice.wait(Until.findObject(appSelector), UI_WAIT_TIMEOUT);
             }
             return app;
         } else {