Start removing some pre-md constants and related code.

ash/common/system/tray/system_tray_item.cc

Index: ash/common/system/tray/system_tray_item.cc
diff --git a/ash/common/system/tray/system_tray_item.cc b/ash/common/system/tray/system_tray_item.cc
index 164a0e419ecc6490163790e075a73de4010549cd..2d34391fd30e4b84173da20bcd5a525f4b9ab7ba 100644
--- a/ash/common/system/tray/system_tray_item.cc
+++ b/ash/common/system/tray/system_tray_item.cc
@@ -42,16 +42,11 @@ void SystemTrayItem::DestroyDetailedView() {}
 void SystemTrayItem::DestroyNotificationView() {}
 
 void SystemTrayItem::TransitionDetailedView() {
-  const int transition_delay =
-      GetTrayConstant(TRAY_POPUP_TRANSITION_TO_DETAILED_DELAY);
-  if (transition_delay <= 0) {
-    DoTransitionToDetailedView();
-    return;
-  }
-  transition_delay_timer_.reset(new base::OneShotTimer());
-  transition_delay_timer_->Start(
-      FROM_HERE, base::TimeDelta::FromMilliseconds(transition_delay), this,
-      &SystemTrayItem::DoTransitionToDetailedView);
+  transition_delay_timer_.Start(
+      FROM_HERE,
+      base::TimeDelta::FromMilliseconds(kTrayDetailedViewTransitionDelayMs),
+      base::Bind(&SystemTray::ShowDetailedView, base::Unretained(system_tray()),
+                 this, 0, true, BUBBLE_USE_EXISTING));
 }
 
 void SystemTrayItem::UpdateAfterLoginStatusChange(LoginStatus status) {}
@@ -84,9 +79,4 @@ bool SystemTrayItem::ShouldShowShelf() const {
   return true;
 }
 
-void SystemTrayItem::DoTransitionToDetailedView() {
-  transition_delay_timer_.reset();
-  system_tray()->ShowDetailedView(this, 0, true, BUBBLE_USE_EXISTING);
-}
-
 }  // namespace ash