[Sharesheet] Missing close check.

Add close check so that sharesheet can't close if it's already
in the process of closing.

Bug: 1153284
Change-Id: I1279240e2ceb9c7769ab96244d8aa3d3393aec11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570914
Auto-Submit: Melissa Zhang <melzhang@chromium.org>
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833517}

chrome/browser/ui/views/sharesheet/sharesheet_bubble_view.cc

@@ -447,7 +447,7 @@ void SharesheetBubbleView::OnWidgetActivationChanged(views::Widget* widget,
   // Catch widgets that are closing due to the user clicking out of the bubble.
   // If |user_selection_made_| we should not close the bubble here as it will be
   // closed in a different code path.
-  if (!active && !user_selection_made_) {
+  if (!active && !user_selection_made_ && !is_bubble_closing_) {
     if (close_callback_) {
       std::move(close_callback_).Run(sharesheet::SharesheetResult::kCancel);
     }