Views: fix tab close button's focus ring in RTL

Also removes the explicit focus ring layout since ImageButton::Layout
takes care of this.

Bug: 854934
Change-Id: Ib49442d1db95577d9e4f7d0497e1b3bd50bf2cbc
Reviewed-on: https://chromium-review.googlesource.com/1124765Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572303}

chrome/browser/ui/views/tabs/tab_close_button.cc

@@ -123,9 +123,8 @@ const char* TabCloseButton::GetClassName() const {
 void TabCloseButton::Layout() {
   ImageButton::Layout();
   if (focus_ring()) {
-    focus_ring()->Layout();
     SkPath path;
-    path.addOval(gfx::RectToSkRect(GetContentsBounds()));
+    path.addOval(gfx::RectToSkRect(GetMirroredRect(GetContentsBounds())));
     focus_ring()->SetPath(path);
   }
 }