Add TrackedPreferenceValidationDelegate

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_
 
 class PrefHashStoreTransaction;
+class TrackedPreferenceValidationObserver;
 
 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| which
   // can update hashes in the corresponding hash store via |transaction|.
   virtual void OnNewValue(const base::Value* value,
                           PrefHashStoreTransaction* transaction) 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.
   // May use |transaction| to check/modify hashes in the corresponding hash
   // store.

[erikwright (departed), 2014/05/14 00:39:26]

If it won't be a constructor parameter (detail of the concrete class) please add
a comment here describing |observer|.

[grt (UTC plus 2), 2014/05/14 18:57:22]

Done.

   virtual bool EnforceAndReport(
       base::DictionaryValue* pref_store_contents,
-      PrefHashStoreTransaction* transaction) const = 0;
+      PrefHashStoreTransaction* transaction,
+      TrackedPreferenceValidationObserver* observer) const = 0;
 };
 
 #endif  // CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_