Reuse NativeThemeAuraDark for cros tray.

ash/common/system/date/date_view.cc

Index: ash/common/system/date/date_view.cc
diff --git a/ash/common/system/date/date_view.cc b/ash/common/system/date/date_view.cc
index e1434d80dbf659899b5d1364ef94ce2de0399353..02444f31aad36dcb6c264fb03e3dcc9eadb84612 100644
--- a/ash/common/system/date/date_view.cc
+++ b/ash/common/system/date/date_view.cc
@@ -71,13 +71,6 @@ base::string16 FormatDayOfWeek(const base::Time& time) {
                         static_cast<size_t>(date_string.length()));
 }
 
-views::Label* CreateLabel() {
-  views::Label* label = new views::Label;
-  label->SetHorizontalAlignment(gfx::ALIGN_LEFT);

[Evan Stade, 2016/08/18 00:38:02]

This alignment is not necessary for the time labels.

The background color is neither necessary nor correct for the time labels (they
don't have auto color readability, and the bg color is set in
SetupLabelForTray). The background color/auto readability adjustments is not
necessary for the date label either, which automatically has a light bg color
set. The 0 opacity disabled subpixel rendering, which is not necessary since the
date label is displayed on a solid bg.

-  label->SetBackgroundColor(SkColorSetARGB(0, 255, 255, 255));
-  return label;
-}
-
 }  // namespace
 
 BaseDateTimeView::~BaseDateTimeView() {
@@ -145,7 +138,8 @@ void BaseDateTimeView::OnLocaleChanged() {
 
 DateView::DateView() : action_(TrayDate::NONE) {
   SetLayoutManager(new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 0));
-  date_label_ = CreateLabel();
+  date_label_ = new views::Label();
+  date_label_->SetHorizontalAlignment(gfx::ALIGN_LEFT);
   date_label_->SetEnabledColor(kHeaderTextColorNormal);
   UpdateTextInternal(base::Time::Now());
   AddChildView(date_label_);
@@ -315,12 +309,13 @@ void TimeView::SetBorderFromLayout(TrayDate::ClockLayout clock_layout) {
 }
 
 void TimeView::SetupLabels() {
-  horizontal_label_.reset(CreateLabel());
+  horizontal_label_.reset(new views::Label());
   SetupLabel(horizontal_label_.get());
-  vertical_label_hours_.reset(CreateLabel());
+  vertical_label_hours_.reset(new views::Label());
   SetupLabel(vertical_label_hours_.get());
-  vertical_label_minutes_.reset(CreateLabel());
+  vertical_label_minutes_.reset(new views::Label());
   SetupLabel(vertical_label_minutes_.get());
+  // TODO(estade): this should use the NativeTheme's secondary text color.
   vertical_label_minutes_->SetEnabledColor(kVerticalClockMinuteColor);
   // Pull the minutes up closer to the hours by using a negative top border.
   vertical_label_minutes_->SetBorder(views::Border::CreateEmptyBorder(