Fixed crash when AddLabelledRowToGridLayout() is called on Mac.

When calling AddView from AddLabelledRowToGridLayout,
released unique_ptr to pass to argument.

Bug: 948287
Change-Id: I71373a27ee7b8c7ae3bf8c1fdb8eed86b806eac2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1644889
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666281}

ui/views/examples/button_sticker_sheet.cc

@@ -56,7 +56,7 @@ void AddLabelledRowToGridLayout(GridLayout* layout,
   const float kRowDoesNotResizeVertically = 0.0;
   const int kPaddingRowHeight = 8;
   layout->StartRow(kRowDoesNotResizeVertically, kStretchyGridColumnSetId);
-  layout->AddView(MakePlainLabel(label_text).get());
+  layout->AddView(MakePlainLabel(label_text).release());
   for (auto& view : views)
     layout->AddView(view.release());
   // This gets added extraneously after the last row, but it doesn't hurt and