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

extensions/browser/extension_prefs.h

 // Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_PREFS_H_
 #define EXTENSIONS_BROWSER_EXTENSION_PREFS_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 305 matching lines @@
   bool HasWipeoutBeenAcknowledged(const std::string& extension_id);
   void SetWipeoutAcknowledged(const std::string& extension_id, bool value);
 
   // Whether the user has been notified about extension with |extension_id|
   // taking over some aspect of the user's settings (homepage, startup pages,
   // or search engine).
   bool HasSettingsApiBubbleBeenAcknowledged(const std::string& extension_id);
   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 HasNtpOverriddenBubbleBeenAcknowledged(const std::string& extension_id);
+  void SetNtpOverriddenBubbleBeenAcknowledged(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
   // acknowledged. This is a fuse. Calling it the first time returns false.
   // Subsequent calls return true. It's not possible through an API to ever
   // reset it. Don't call it unless you mean it!
   bool SetAlertSystemFirstRun();
 
   // Checks if extensions are blacklisted by default, by policy.
   // The ManagementPolicy::Provider methods also take this into account, and
@@ skipping 371 matching lines @@
   bool extensions_disabled_;
 
   ObserverList<ExtensionPrefsObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefs);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_PREFS_H_