Allow SceneOverlay layers to be removed from tree

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java
index 49008e624f51020df64146435360cd23bd517533..9fe7afefe9467110ffbd648176a697644b8bbdcc 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java
@@ -803,6 +803,11 @@ public class OverlayPanel extends OverlayPanelAnimation implements ActivityState
     }
 
     @Override
+    public boolean isSceneOverlayTreeShowing() {
+        return isShowing();
+    }
+
+    @Override
     public EventFilter getEventFilter() {
         return mEventFilter;
     }