New post-sideload UI:

chrome/browser/extensions/external_install_ui.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTERNAL_INSTALL_UI_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTERNAL_INSTALL_UI_H_
+
+class Browser;
+class ExtensionService;
+
+namespace extensions {
+
+class Extension;
+
+// Adds/Removes a global error informing the user that an external extension
+// was installed.
+bool AddExternalInstallError(ExtensionService* service,
+                             const Extension* extension);
+void RemoveExternalInstallError(ExtensionService* service);
+
+// Used for testing.
+bool HasExternalInstallError(ExtensionService* service);
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_INSTALL_UI_H_