Remove unnecessary waitForIdleSync

bug: 31640349

Change-Id: Iebbb431d946c1c75b2cfce3e7a9d5a9fc132fba0
diff --git a/tests/tests/uirendering/src/android/uirendering/cts/testinfrastructure/ActivityTestBase.java b/tests/tests/uirendering/src/android/uirendering/cts/testinfrastructure/ActivityTestBase.java
index 458f69b..ae915db 100644
--- a/tests/tests/uirendering/src/android/uirendering/cts/testinfrastructure/ActivityTestBase.java
+++ b/tests/tests/uirendering/src/android/uirendering/cts/testinfrastructure/ActivityTestBase.java
@@ -125,7 +125,6 @@
     }
 
     public Bitmap takeScreenshot(Point testOffset) {
-        getInstrumentation().waitForIdleSync();
         Bitmap source = getInstrumentation().getUiAutomation().takeScreenshot();
         return Bitmap.createBitmap(source, testOffset.x, testOffset.y, TEST_WIDTH, TEST_HEIGHT);
     }