Add a chrome://nacl page to show if NaCl is enabled and if PNaCl is installed.

chrome/browser/ui/webui/nacl_ui.h

Index: chrome/browser/ui/webui/nacl_ui.h
diff --git a/chrome/browser/ui/webui/nacl_ui.h b/chrome/browser/ui/webui/nacl_ui.h
new file mode 100644
index 0000000000000000000000000000000000000000..3971b4dcb74439f7103005536e416879a8d66564
--- /dev/null
+++ b/chrome/browser/ui/webui/nacl_ui.h
@@ -0,0 +1,19 @@
+// 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_UI_WEBUI_NACL_UI_H_
+#define CHROME_BROWSER_UI_WEBUI_NACL_UI_H_
+
+#include "content/public/browser/web_ui_controller.h"
+
+// The Web UI handler for about:nacl.
+class NaClUI : public content::WebUIController {
+ public:
+  explicit NaClUI(content::WebUI* web_ui);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NaClUI);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_NACL_UI_H_