[Sharesheet] Fix off by 1 error.

Target counter currently has an off by 1 error.

Bug: 1131108
Change-Id: Ib180c0fd4c165be6708adc9b008fcee209b41595
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2423752Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Melissa Zhang <melzhang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809632}

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

@@ -247,7 +247,7 @@ void SharesheetBubbleView::PopulateLayoutsWithTargets(
 
     auto target_view = std::make_unique<SharesheetTargetButton>(
         this, target.display_name, secondary_display_name, &target.icon);
-    target_view->set_tag(++target_counter);
+    target_view->set_tag(target_counter++);
 
     layout_for_target->AddView(std::move(target_view));
   }