Add an automatic settings reset banner.

chrome/browser/prefs/tracked/tracked_preference.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 CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_
 #define CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_
 
 namespace base {
 class DictionaryValue;
 class Value;
 }
 
 // A TrackedPreference tracks changes to an individual preference, reporting and
 // reacting to them according to preference-specific and browser-wide policies.
 class TrackedPreference {
  public:
   virtual ~TrackedPreference() {}
 
   // Notifies the underlying TrackedPreference about its new |value|.
   virtual void OnNewValue(const base::Value* value) const = 0;
 
   // Verifies that the value of this TrackedPreference in |pref_store_contents|
   // is valid. Responds to verification failures according to
   // preference-specific and browser-wide policy and reports results to via UMA.
-  virtual void EnforceAndReport(
+  // Returns true if a setting was reset, false otherwise.
+  virtual bool EnforceAndReport(
       base::DictionaryValue* pref_store_contents) const = 0;
 };
 
 #endif  // CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_