Add ability to specify extra insets for a view via its border.

ui/views/border.h

Index: ui/views/border.h
diff --git a/ui/views/border.h b/ui/views/border.h
index d30cc7ca0b00e2882b2b5288d9b058a98fa3858d..3a52df514e55513aeaf35e92fe4c7f42632d37e9 100644
--- a/ui/views/border.h
+++ b/ui/views/border.h
@@ -73,6 +73,11 @@ class VIEWS_EXPORT Border {
                                                         int right,
                                                         SkColor color);
 
+  // Adds extra, unpainted insets to |border|.

[sky, 2016/11/03 19:24:49]

This seems like a nice way to avoid changing all borders. How about a better
comment though with an example?

[Evan Stade, 2016/11/04 03:16:39]

OK, I tried (I also tried some ASCII art but gave up after flailing for a bit).

+  static std::unique_ptr<Border> AddInteriorPadding(
+      std::unique_ptr<Border> border,
+      const gfx::Insets& insets);
+
   // Creates a Border from the specified Painter.
   // |insets| define size of an area allocated for a Border.
   static std::unique_ptr<Border> CreateBorderPainter(