Call onShow/onHide when visibility changes on -1 screen.

Bug: 10089616
Change-Id: I4365432d5ff699b3722ca3f30713e0c490d0e4ed
diff --git a/src/com/android/launcher3/Workspace.java b/src/com/android/launcher3/Workspace.java
index 91f5396..b14ceb2 100644
--- a/src/com/android/launcher3/Workspace.java
+++ b/src/com/android/launcher3/Workspace.java
@@ -770,6 +770,13 @@
 
     protected void onWindowVisibilityChanged (int visibility) {
         mLauncher.onWindowVisibilityChanged(visibility);
+        if (mCustomContentShowing && mCustomContentCallbacks != null) {
+            if (visibility == View.VISIBLE) {
+                mCustomContentCallbacks.onShow();
+            } else if (visibility == View.GONE) {
+                mCustomContentCallbacks.onHide();
+            }
+        }
     }
 
     @Override