Add an extension bubble explaining which extensions are in dev mode.

chrome/browser/extensions/extension_message_bubble.h

Index: chrome/browser/extensions/extension_message_bubble.h
diff --git a/chrome/browser/extensions/extension_message_bubble.h b/chrome/browser/extensions/extension_message_bubble.h
new file mode 100644
index 0000000000000000000000000000000000000000..bdce711af2dad9fc3fd163c0e85495ffe30504f2
--- /dev/null
+++ b/chrome/browser/extensions/extension_message_bubble.h
@@ -0,0 +1,34 @@
+// Copyright (c) 2013 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_EXTENSION_MESSAGE_BUBBLE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_BUBBLE_H_
+
+#include "base/bind.h"
+
+class Browser;
+
+namespace extensions {
+
+// The interface between the SuspiciousExtensionBubble bubble and its
+// controller.
+class ExtensionMessageBubble {
+ public:
+  // Setup the callback for when the action button is clicked in the
+  // bubble.
+  virtual void OnActionButtonClicked(const base::Closure& callback) = 0;
+
+  // Setup the callback for when the dismiss button is clicked.
+  virtual void OnDismissButtonClicked(const base::Closure& callback) = 0;
+
+  // Setup the callback for when the link is clicked in the bubble.
+  virtual void OnLinkClicked(const base::Closure& callback) = 0;
+
+  // Instruct the bubble to appear.
+  virtual void Show() = 0;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_MESSAGE_BUBBLE_H_