Fix footnote focus order in BubbleFrameView

This change inserts the footnote container before the close button so
that it comes before caption buttons in focus order. Ideally there'd be
a good way to express inserting it "after the contents view" but afaict
there's no such notion in here.

Bug: 1061352
Change-Id: I460588ae1baee6c26d6fbc7aa7037789d771497b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2335337
Auto-Submit: Peter Boström <pbos@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794514}

ui/views/bubble/bubble_frame_view.cc

@@ -532,9 +532,13 @@ void BubbleFrameView::SetFootnoteView(std::unique_ptr<View> view) {
   delete footnote_container_;
   footnote_container_ = nullptr;
   if (view) {
+    // Insert the footnote container before |close_| so that the footnote is
+    // inserted before caption buttons in the focus cycle.
     int radius = bubble_border_ ? bubble_border_->corner_radius() : 0;
-    footnote_container_ = AddChildView(std::make_unique<FootnoteContainerView>(
-        footnote_margins_, std::move(view), radius));
+    footnote_container_ =
+        AddChildViewAt(std::make_unique<FootnoteContainerView>(
+                           footnote_margins_, std::move(view), radius),
+                       GetIndexOf(close_));
   }
   InvalidateLayout();
 }