Use EventRouter::Get instead of ExtensionSystem::Get(browser_context)->event_router()

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

Index: chrome/browser/ui/webui/extensions/command_handler.h
diff --git a/chrome/browser/ui/webui/extensions/command_handler.h b/chrome/browser/ui/webui/extensions/command_handler.h
index c2f557385703450a05fc6de5dd0c0f6112d1e391..817cced6870ce8ad5cb8f5206dc7e85d35f1354c 100644
--- a/chrome/browser/ui/webui/extensions/command_handler.h
+++ b/chrome/browser/ui/webui/extensions/command_handler.h
@@ -5,10 +5,10 @@
 #ifndef CHROME_BROWSER_UI_WEBUI_EXTENSIONS_COMMAND_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_EXTENSIONS_COMMAND_HANDLER_H_
 
+#include "base/scoped_observer.h"
 #include "base/compiler_specific.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_ui_message_handler.h"
+#include "extensions/browser/extension_registry_observer.h"
 
 namespace base {
 class DictionaryValue;
@@ -22,6 +22,7 @@ class WebUIDataSource;
 namespace extensions {
 class Command;
 class CommandService;
+class ExtensionRegistry;
 }
 
 class Extension;
@@ -31,7 +32,7 @@ namespace extensions {
 
 // The handler page for the Extension Commands UI overlay.
 class CommandHandler : public content::WebUIMessageHandler,
-                       public content::NotificationObserver {
+                       public extensions::ExtensionRegistryObserver {
  public:
   explicit CommandHandler(Profile* profile);
   virtual ~CommandHandler();
@@ -42,12 +43,16 @@ class CommandHandler : public content::WebUIMessageHandler,
   // WebUIMessageHandler implementation.
   virtual void RegisterMessages() OVERRIDE;
 
-  // NotificationObserver implementation.
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
-
  private:
+  // extension::ExtensionRegistryObserver implementation.

[Devlin, 2014/05/16 17:34:04]

nit: extensions::

+  virtual void OnExtensionLoaded(
+      content::BrowserContext* browser_context,
+      const extensions::Extension* extension) OVERRIDE;
+  virtual void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const extensions::Extension* extension,
+      extensions::UnloadedExtensionInfo::Reason reason) OVERRIDE;
+
    // Update the list of extension commands in the config UI.
   void UpdateCommandDataOnPage();
 
@@ -72,10 +77,12 @@ class CommandHandler : public content::WebUIMessageHandler,
   // |commands|.
   void GetAllCommands(base::DictionaryValue* commands);
 
-  content::NotificationRegistrar registrar_;
-
   Profile* profile_;
 
+  ScopedObserver<extensions::ExtensionRegistry,
+                 extensions::ExtensionRegistryObserver>
+      extension_registry_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(CommandHandler);
 };