Destroy mOptionalButtonController in TopToolbarCoordinator#destroy

Bug: 1069829
Change-Id: Ia78655f876347774423a26cfa98b8b363d498c87
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2148025Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Patrick Noland <pnoland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759010}

chrome/android/java/src/org/chromium/chrome/browser/toolbar/top/TopToolbarCoordinator.java

@@ -72,7 +72,7 @@ public class TopToolbarCoordinator implements Toolbar {
     private @Nullable StartSurfaceToolbarCoordinator mStartSurfaceToolbarCoordinator;
 
     private final IdentityDiscController mIdentityDiscController;
-    private final OptionalBrowsingModeButtonController mOptionalButtonController;
+    private OptionalBrowsingModeButtonController mOptionalButtonController;
 
     private HomepageManager.HomepageStateListener mHomepageStateListener =
             new HomepageManager.HomepageStateListener() {
@@ -203,6 +203,11 @@ public class TopToolbarCoordinator implements Toolbar {
         } else if (mStartSurfaceToolbarCoordinator != null) {
             mStartSurfaceToolbarCoordinator.destroy();
         }
+
+        if (mOptionalButtonController != null) {
+            mOptionalButtonController.destroy();
+            mOptionalButtonController = null;
+        }
     }
 
     @Override