Signin screen and locked screen status area focus advancing

ash/common/system/tray/system_tray_notifier.cc

Index: ash/common/system/tray/system_tray_notifier.cc
diff --git a/ash/common/system/tray/system_tray_notifier.cc b/ash/common/system/tray/system_tray_notifier.cc
index 3629b1bde5ff2b8785d6031453afa93459c32c73..7d93a6001a72aeb26ef74458d4097c3ea8fd134d 100644
--- a/ash/common/system/tray/system_tray_notifier.cc
+++ b/ash/common/system/tray/system_tray_notifier.cc
@@ -8,6 +8,7 @@
 #include "ash/common/system/audio/audio_observer.h"
 #include "ash/common/system/date/clock_observer.h"
 #include "ash/common/system/ime/ime_observer.h"
+#include "ash/common/system/status_area_focus_observer.h"
 #include "ash/common/system/update/update_observer.h"
 #include "ash/common/system/user/user_observer.h"
 
@@ -155,6 +156,21 @@ void SystemTrayNotifier::NotifyUpdateRecommended(const UpdateInfo& info) {
                     OnUpdateRecommended(info));
 }
 
+void SystemTrayNotifier::AddStatusAreaFocusObserver(
+    StatusAreaFocusObserver* observer) {
+  status_area_focus_observers_.AddObserver(observer);
+}
+
+void SystemTrayNotifier::RemoveStatusAreaFocusObserver(
+    StatusAreaFocusObserver* observer) {
+  status_area_focus_observers_.RemoveObserver(observer);
+}
+
+void SystemTrayNotifier::NotifyWillReturnFocusToWebContents(bool reverse) {
+  FOR_EACH_OBSERVER(StatusAreaFocusObserver, status_area_focus_observers_,
+                    OnWillReturnFocusToWebContents(reverse));
+}
+
 void SystemTrayNotifier::AddUserObserver(UserObserver* observer) {
   user_observers_.AddObserver(observer);
 }