Replace chrome::NOTIFICATION_EXTENSION_WARNING_CHANGED message with observer pattern

chrome/browser/extensions/extension_warning_set.cc

Index: chrome/browser/extensions/extension_warning_set.cc
diff --git a/chrome/browser/extensions/extension_warning_set.cc b/chrome/browser/extensions/extension_warning_set.cc
index c358f54eea4261390fd9c9851bd666cb9d651fec..af9d3f0245248c5f1086a1e730db381ca795223d 100644
--- a/chrome/browser/extensions/extension_warning_set.cc
+++ b/chrome/browser/extensions/extension_warning_set.cc
@@ -314,6 +314,16 @@ void ExtensionWarningService::NotifyWarningsOnUI(
   warning_service->AddWarnings(warnings.Pass());
 }
 
+void ExtensionWarningService::AddObserver(
+    ExtensionWarningService::Observer* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void ExtensionWarningService::RemoveObserver(
+    ExtensionWarningService::Observer* observer) {
+  observer_list_.RemoveObserver(observer);
+}
+
 void ExtensionWarningService::SuppressBadgeForCurrentWarnings() {
   DCHECK(CalledOnValidThread());
   badge_suppressions_.insert(warnings_.begin(), warnings_.end());
@@ -322,10 +332,7 @@ void ExtensionWarningService::SuppressBadgeForCurrentWarnings() {
 
 void ExtensionWarningService::NotifyWarningsChanged() {
   DCHECK(CalledOnValidThread());
-  content::NotificationService::current()->Notify(
-      chrome::NOTIFICATION_EXTENSION_WARNING_CHANGED,
-      content::Source<Profile>(profile_),
-      content::NotificationService::NoDetails());
+  FOR_EACH_OBSERVER(Observer, observer_list_, ExtensionWarningsChanged());
 }
 
 void ExtensionWarningService::UpdateWarningBadge() {