[Extensions Page] Add a listener on extension list for "hasExtensions" changing

chrome/browser/extensions/api/developer_private/developer_private_api.h

Index: chrome/browser/extensions/api/developer_private/developer_private_api.h
diff --git a/chrome/browser/extensions/api/developer_private/developer_private_api.h b/chrome/browser/extensions/api/developer_private/developer_private_api.h
index 8e2e013a10bddf9738a29988bc1d3c9b1df86c46..9389d946c80ec8d34919a1dad828f5120ff06b4a 100644
--- a/chrome/browser/extensions/api/developer_private/developer_private_api.h
+++ b/chrome/browser/extensions/api/developer_private/developer_private_api.h
@@ -83,11 +83,9 @@ class DeveloperPrivateEventRouter : public ExtensionRegistryObserver,
   void OnExtensionUnloaded(content::BrowserContext* browser_context,
                            const Extension* extension,
                            UnloadedExtensionInfo::Reason reason) override;
-  void OnExtensionWillBeInstalled(content::BrowserContext* browser_context,
-                                  const Extension* extension,
-                                  bool is_update,
-                                  bool from_ephemeral,
-                                  const std::string& old_name) override;
+  void OnExtensionInstalled(content::BrowserContext* browser_context,
+                            const Extension* extension,
+                            bool is_update) override;
   void OnExtensionUninstalled(content::BrowserContext* browser_context,
                               const Extension* extension,
                               extensions::UninstallReason reason) override;