[M98] Unregister Accelerators when AccessiblePaneView is destroyed.

This CL makes sure that a focus change listener and all Accelerators are
unregistered when the AccessiblePaneView is going to be destroyed.

(cherry picked from commit 7125ad1)

Bug: 1284293
Change-Id: Icd11523be7ab5728e181148a8fd1baec5349513e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3429899
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Illia Klimov <elklm@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#966217}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3450213
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/branch-heads/4758@{#1121}
Cr-Branched-From: 4a2cf4b-refs/heads/main@{#950365}

ui/views/accessible_pane_view.cc

@@ -54,7 +54,7 @@ AccessiblePaneView::AccessiblePaneView()
 
 AccessiblePaneView::~AccessiblePaneView() {
   if (pane_has_focus_) {
-    focus_manager_->RemoveFocusChangeListener(this);
+    RemovePaneFocus();
   }
 }