Allow SceneOverlay layers to be removed from tree

chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java
index 1c3d5fb14cadd9e53e82fcc333e232c54d46ba80..7cc8d942ad3e54cb3dae0946e25d75d418d0ac9b 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java
@@ -126,6 +126,13 @@ public class StripLayoutHelperManager implements SceneOverlay {
     }
 
     @Override
+    public boolean isSceneOverlayTreeShowing() {
+        // TODO(mdjones): This matches existing behavior but can be improved to return false if
+        // the top controls offset is equal to the top controls height.
+        return true;
+    }
+
+    @Override
     public EventFilter getEventFilter() {
         return mEventFilter;
     }