Add TrackedPreferenceValidationDelegate

chrome/browser/prefs/tracked/tracked_atomic_preference.h

Index: chrome/browser/prefs/tracked/tracked_atomic_preference.h
diff --git a/chrome/browser/prefs/tracked/tracked_atomic_preference.h b/chrome/browser/prefs/tracked/tracked_atomic_preference.h
index 57422b1ba5f446e3ffb7585f26b61a973bb10e50..9a58115a07f65cc76da630a5a6d635f7b1dfaa0f 100644
--- a/chrome/browser/prefs/tracked/tracked_atomic_preference.h
+++ b/chrome/browser/prefs/tracked/tracked_atomic_preference.h
@@ -28,7 +28,8 @@ class TrackedAtomicPreference : public TrackedPreference {
                           PrefHashStoreTransaction* transaction) const OVERRIDE;
   virtual bool EnforceAndReport(
       base::DictionaryValue* pref_store_contents,
-      PrefHashStoreTransaction* transaction) const OVERRIDE;
+      PrefHashStoreTransaction* transaction,
+      TrackedPreferenceValidationObserver* observer) const OVERRIDE;

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

This could probably be a constructor parameter / member, right? It doesn't
change from call to call?

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

I chose to make it a parameter here to avoid ownership issues. As a ctor
parameter, it either needs to be a naked pointer documented as being owned by
the TrackedPreference's owner, or it needs to be refcounted. Is there another
option I'm missing? Do you prefer one of those?

[erikwright (departed), 2014/05/14 21:24:06]

I prefer it being a raw pointer because there is no case for using a different
observer in different invocations. You can mention that it must outlive the
TrackedPreference if you like. But the TrackedPreference is owned by the
PrefHashFilter, so the lifecycle relationship is unambiguous.

[grt (UTC plus 2), 2014/05/15 01:43:11]

sgtm. Done.

 
  private:
   const std::string pref_path_;