Remove unused references to NativeTheme in TrayPopupItemStyle.

ash/common/system/tray/hover_highlight_view.cc

Index: ash/common/system/tray/hover_highlight_view.cc
diff --git a/ash/common/system/tray/hover_highlight_view.cc b/ash/common/system/tray/hover_highlight_view.cc
index 818c35acbd9571528047763d7ffe865c94bc53d2..739810c9076559400fdefd1f6149f22c1f317918 100644
--- a/ash/common/system/tray/hover_highlight_view.cc
+++ b/ash/common/system/tray/hover_highlight_view.cc
@@ -205,15 +205,14 @@ void HoverHighlightView::DoAddIconAndLabelsMd(
   text_label_ = TrayPopupUtils::CreateDefaultLabel();
   text_label_->SetText(text);
   text_label_->SetEnabled(enabled());
-  TrayPopupItemStyle style(GetNativeTheme(), font_style);
+  TrayPopupItemStyle style(font_style);
   style.SetupLabel(text_label_);
 
   tri_view_->AddView(TriView::Container::CENTER, text_label_);
   if (!sub_text.empty()) {
     sub_text_label_ = TrayPopupUtils::CreateDefaultLabel();
     sub_text_label_->SetText(sub_text);
-    TrayPopupItemStyle sub_style(GetNativeTheme(),
-                                 TrayPopupItemStyle::FontStyle::CAPTION);
+    TrayPopupItemStyle sub_style(TrayPopupItemStyle::FontStyle::CAPTION);
     sub_style.set_color_style(TrayPopupItemStyle::ColorStyle::INACTIVE);
     sub_style.SetupLabel(sub_text_label_);
     tri_view_->AddView(TriView::Container::CENTER, sub_text_label_);