Settings Overides -- warn user when extensions override their NTP.

extensions/browser/extension_prefs.h

Index: extensions/browser/extension_prefs.h
diff --git a/extensions/browser/extension_prefs.h b/extensions/browser/extension_prefs.h
index 4ff16a578adacb50652c5f78c72d815e16620099..5a5b63feaa07a8363fcfd89dbd2cbf7942380484 100644
--- a/extensions/browser/extension_prefs.h
+++ b/extensions/browser/extension_prefs.h
@@ -323,6 +323,12 @@ class ExtensionPrefs : public ExtensionScopedPrefs, public KeyedService {
   void SetSettingsApiBubbleBeenAcknowledged(const std::string& extension_id,
                                             bool value);
 
+  // Whether the user has been notified about extension with |extension_id|
+  // overriding the new tab page.
+  bool HasNtpControlledBubbleBeenAcknowledged(const std::string& extension_id);

[Yoyo Zhou, 2014/04/23 00:04:24]

likewise, Overridden instead of Controlled?

[Finnur, 2014/04/23 13:51:35]

Done.

+  void SetNtpControlledBubbleBeenAcknowledged(const std::string& extension_id,
+                                              bool value);
+
   // Returns true if the extension notification code has already run for the
   // first time for this profile. Currently we use this flag to mean that any
   // extensions that would trigger notifications should get silently