weblayer: ensure DisplayCutoutController is destroyed

BUG=1140143
TEST=none

Change-Id: If89a59ce8992c13ef269b24dbe0a1458c72718fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485842Reviewed-by: Evan Stade <estade@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818705}

weblayer/browser/java/org/chromium/weblayer_private/TabImpl.java

@@ -931,6 +931,11 @@ public final class TabImpl extends ITab.Stub implements LoginPrompt.Observer {
             }
         }
 
+        if (mDisplayCutoutController != null) {
+            mDisplayCutoutController.destroy();
+            mDisplayCutoutController = null;
+        }
+
         // This is called to ensure a listener is removed from the WebContents.
         setScrollOffsetsEnabled(false);