Add WebNotificationTray to the status area

ash/system/tray/system_tray.cc

Index: ash/system/tray/system_tray.cc
diff --git a/ash/system/tray/system_tray.cc b/ash/system/tray/system_tray.cc
index 707c962a5c95939d9cb37f1c8f69ce857397e2ce..0b6e2df5b73e35e202cbdee419a84200c0277d94 100644
--- a/ash/system/tray/system_tray.cc
+++ b/ash/system/tray/system_tray.cc
@@ -138,7 +138,8 @@ SystemTray::SystemTray()
       update_observer_(NULL),
       user_observer_(NULL),
       should_show_launcher_(false),
-      default_bubble_height_(0) {
+      default_bubble_height_(0),
+      hide_notifications_(false) {
   tray_container_ = new internal::SystemTrayContainer;
   tray_container_->SetLayoutManager(new views::BoxLayout(
       views::BoxLayout::kHorizontal, 0, 0, 0));
@@ -298,6 +299,16 @@ void SystemTray::UpdateAfterShelfAlignmentChange(ShelfAlignment alignment) {
   }
 }
 
+void SystemTray::SetHideNotifications(bool hide_notifications) {
+  if (notification_bubble_.get())
+    notification_bubble_->SetVisible(!hide_notifications);
+  hide_notifications_ = hide_notifications;
+}
+
+bool SystemTray::IsBubbleVisible() const {
+  return bubble_.get() && bubble_->IsVisible();
+}
+
 bool SystemTray::CloseBubbleForTest() const {
   if (!bubble_.get())
     return false;
@@ -462,6 +473,8 @@ void SystemTray::UpdateNotificationBubble() {
   if (arrow_offset >= 0)
     init_params.arrow_offset = arrow_offset;
   notification_bubble_->InitView(init_params);
+  if (hide_notifications_)
+    notification_bubble_->SetVisible(false);
 }
 
 void SystemTray::UpdateNotificationAnchor() {