Omit dimmed children from accessibility nav in SlidingPaneLayout

Bug 8657571

Change-Id: I84be757dfe7d4156b52552ee74e72ad14b396d2d
diff --git a/v4/java/android/support/v4/widget/SlidingPaneLayout.java b/v4/java/android/support/v4/widget/SlidingPaneLayout.java
index 67c7262..e85eb71 100644
--- a/v4/java/android/support/v4/widget/SlidingPaneLayout.java
+++ b/v4/java/android/support/v4/widget/SlidingPaneLayout.java
@@ -261,6 +261,7 @@
         setWillNotDraw(false);
 
         ViewCompat.setAccessibilityDelegate(this, new AccessibilityDelegate());
+        ViewCompat.setImportantForAccessibility(this, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
 
         mDragHelper = ViewDragHelper.create(this, 0.5f, new DragHelperCallback());
         mDragHelper.setEdgeTrackingEnabled(ViewDragHelper.EDGE_LEFT);