Add update available icon in system tray

chrome/browser/upgrade_detector.cc

Index: chrome/browser/upgrade_detector.cc
diff --git a/chrome/browser/upgrade_detector.cc b/chrome/browser/upgrade_detector.cc
index 2dfd1a91560d353cf9753dfa8654eeb8046c4483..68215d240a6d08fcd005d3093f3069c3dc9c19b6 100644
--- a/chrome/browser/upgrade_detector.cc
+++ b/chrome/browser/upgrade_detector.cc
@@ -87,6 +87,11 @@ void UpgradeDetector::NotifyUpgradeRecommended() {
   }
 }
 
+void UpgradeDetector::NotifyUpdateOverCellularAvailable() {
+  for (auto& observer : observer_list_)
+    observer.OnUpdateOverCellularAvailable();
+}
+
 void UpgradeDetector::TriggerCriticalUpdate() {
   const base::TimeDelta idle_timer = UseTestingIntervals() ?
       base::TimeDelta::FromSeconds(kIdleRepeatingTimerWait) :
@@ -138,3 +143,11 @@ void UpgradeDetector::IdleCallback(ui::IdleState state) {
       break;
   }
 }
+
+void UpgradeDetector::AddObserver(UpgradeObserver* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void UpgradeDetector::RemoveObserver(UpgradeObserver* observer) {
+  observer_list_.RemoveObserver(observer);
+}