Replace chrome::NOTIFICATION_EXTENSION_WARNING_CHANGED message with observer pattern

chrome/browser/ui/webui/extensions/extension_settings_handler.h

Index: chrome/browser/ui/webui/extensions/extension_settings_handler.h
diff --git a/chrome/browser/ui/webui/extensions/extension_settings_handler.h b/chrome/browser/ui/webui/extensions/extension_settings_handler.h
index fce0fe01c15b21b8c323636b3aaab6b8e4b63c67..cb5d0b83a70b86a4b680018f4571ab17c4f38e10 100644
--- a/chrome/browser/ui/webui/extensions/extension_settings_handler.h
+++ b/chrome/browser/ui/webui/extensions/extension_settings_handler.h
@@ -13,6 +13,7 @@
 #include "chrome/browser/api/prefs/pref_change_registrar.h"
 #include "chrome/browser/extensions/extension_install_ui.h"
 #include "chrome/browser/extensions/extension_uninstall_dialog.h"
+#include "chrome/browser/extensions/extension_warning_set.h"
 #include "chrome/common/extensions/extension_resource.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/notification_observer.h"
@@ -35,7 +36,6 @@ class ListValue;
 namespace extensions {
 class Extension;
 class ExtensionHost;
-class ExtensionWarningService;
 class ManagementPolicy;
 }
 
@@ -55,11 +55,13 @@ struct ExtensionPage {
 };
 
 // Extension Settings UI handler.
-class ExtensionSettingsHandler : public content::WebUIMessageHandler,
-                                 public content::NotificationObserver,
-                                 public content::WebContentsObserver,
-                                 public ui::SelectFileDialog::Listener,
-                                 public ExtensionUninstallDialog::Delegate {
+class ExtensionSettingsHandler
+    : public content::WebUIMessageHandler,
+      public content::NotificationObserver,
+      public content::WebContentsObserver,
+      public ui::SelectFileDialog::Listener,
+      public ExtensionUninstallDialog::Delegate,
+      public extensions::ExtensionWarningService::Observer {
  public:
   ExtensionSettingsHandler();
   virtual ~ExtensionSettingsHandler();
@@ -109,6 +111,9 @@ class ExtensionSettingsHandler : public content::WebUIMessageHandler,
   virtual void ExtensionUninstallAccepted() OVERRIDE;
   virtual void ExtensionUninstallCanceled() OVERRIDE;
 
+  // extensions::ExtensionWarningService::Observer implementation.
+  virtual void ExtensionWarningsChanged() OVERRIDE;
+
   // Helper method that reloads all unpacked extensions.
   void ReloadUnpackedExtensions();