Display dialog when app install succeeds / fails on Athena

athena/extensions/shell/extensions_delegate_impl.cc

Index: athena/extensions/shell/extensions_delegate_impl.cc
diff --git a/athena/extensions/shell/extensions_delegate_impl.cc b/athena/extensions/shell/extensions_delegate_impl.cc
index 56e507954f632b4f1f49a5a95a36fc5642006529..e9a6ba8a44faafbc9fc3f408914006f7ae435ecb 100644
--- a/athena/extensions/shell/extensions_delegate_impl.cc
+++ b/athena/extensions/shell/extensions_delegate_impl.cc
@@ -41,6 +41,10 @@ class ShellExtensionsDelegate : public ExtensionsDelegate {
 
   virtual bool UnloadApp(const std::string& app_id) override { return false; }
 
+  virtual extensions::ExtensionInstallUI* CreateExtensionInstallUI() override {
+    return NULL;
+  }
+
   content::BrowserContext* context_;
   extensions::ShellExtensionSystem* extension_system_;
   extensions::ExtensionSet shell_extensions_;