Fix IME tray bubble (and other tray bubble views).

ui/views/bubble/bubble_dialog_delegate.cc

Index: ui/views/bubble/bubble_dialog_delegate.cc
diff --git a/ui/views/bubble/bubble_dialog_delegate.cc b/ui/views/bubble/bubble_dialog_delegate.cc
index 29105aa3acc305f2328a2fe6d913e954c6bad163..dd1b2eea6420fdfea199431f4fce0622fe791bf3 100644
--- a/ui/views/bubble/bubble_dialog_delegate.cc
+++ b/ui/views/bubble/bubble_dialog_delegate.cc
@@ -298,6 +298,12 @@ void BubbleDialogDelegateView::UpdateColorsFromTheme(
   BubbleFrameView* frame_view = GetBubbleFrameView();
   if (frame_view)
     frame_view->bubble_border()->set_background_color(color());
+
+  // When there's an opaque layer, the bubble border background won't show
+  // through, so explicitly paint a background color.
+  set_background(layer() && layer()->fills_bounds_opaquely()
+                     ? Background::CreateSolidBackground(color())
+                     : nullptr);
 }
 
 void BubbleDialogDelegateView::HandleVisibilityChanged(Widget* widget,