Write last_modified date to Content Settings in the PrefProvider

components/content_settings/core/browser/content_settings_pref_provider.h

Index: components/content_settings/core/browser/content_settings_pref_provider.h
diff --git a/components/content_settings/core/browser/content_settings_pref_provider.h b/components/content_settings/core/browser/content_settings_pref_provider.h
index 9f33e158f6e21b8ffafa08e48319ced333261fa0..e8520260a1d9ef01e26fb6daf67c3c04d9c58371 100644
--- a/components/content_settings/core/browser/content_settings_pref_provider.h
+++ b/components/content_settings/core/browser/content_settings_pref_provider.h
@@ -32,7 +32,7 @@ class PrefProvider : public ObservableProvider {
  public:
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
-  PrefProvider(PrefService* prefs, bool incognito);
+  PrefProvider(PrefService* prefs, bool incognito, bool store_last_modified);
   ~PrefProvider() override;
 
   // ProviderInterface implementations.
@@ -47,6 +47,13 @@ class PrefProvider : public ObservableProvider {
                          const ResourceIdentifier& resource_identifier,
                          base::Value* value) override;
 
+  // Returns the |last_modified| date of a setting.
+  base::Time GetWebsiteSettingLastModified(
+      const ContentSettingsPattern& primary_pattern,
+      const ContentSettingsPattern& secondary_pattern,
+      ContentSettingsType content_type,
+      const ResourceIdentifier& resource_identifier);
+
   void ClearAllContentSettingsRules(ContentSettingsType content_type) override;
 
   void ShutdownOnUIThread() override;