Speculative fix for incorrect tray stylus button background size

This fix makes sure the background for the stylus button
is explicitly updated any time it's visibility changes.

Bug: 1030268
Change-Id: I5141051f156258e1e68317f11fa69fb416db22fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2048764Reviewed-by: Tim Song <tengs@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740407}

ash/system/palette/palette_tray.cc

@@ -591,10 +591,13 @@ bool PaletteTray::HasSeenStylus() {
 }
 
 void PaletteTray::UpdateIconVisibility() {
-  SetVisiblePreferred(HasSeenStylus() && is_palette_enabled_ &&
-                      stylus_utils::HasStylusInput() &&
-                      ShouldShowOnDisplay(this) &&
-                      palette_utils::IsInUserSession());
+  bool visible_preferred = HasSeenStylus() && is_palette_enabled_ &&
+                           stylus_utils::HasStylusInput() &&
+                           ShouldShowOnDisplay(this) &&
+                           palette_utils::IsInUserSession();
+  SetVisiblePreferred(visible_preferred);
+  if (visible_preferred)
+    UpdateAfterShelfChange();
 }
 
 }  // namespace ash

ash/system/tray/tray_background_view.cc

@@ -354,6 +354,7 @@ void TrayBackgroundView::CloseBubble() {}
 void TrayBackgroundView::ShowBubble(bool show_by_click) {}
 
 void TrayBackgroundView::UpdateAfterShelfChange() {
+  UpdateBackground();
   tray_container_->UpdateAfterShelfChange();
 }