Remove last usage functions from HostContentSettingsMap and clean up prefs

chrome/browser/permissions/permission_manager.cc

Index: chrome/browser/permissions/permission_manager.cc
diff --git a/chrome/browser/permissions/permission_manager.cc b/chrome/browser/permissions/permission_manager.cc
index e890aea26b0a94bb4ec5f78a184249846e77bb7d..145868d29d19fa29401cb62dfe663e0a5116463d 100644
--- a/chrome/browser/permissions/permission_manager.cc
+++ b/chrome/browser/permissions/permission_manager.cc
@@ -425,21 +425,6 @@ PermissionStatus PermissionManager::GetPermissionStatus(
                              requesting_origin, embedding_origin);
 }
 
-void PermissionManager::RegisterPermissionUsage(PermissionType permission,
-                                                const GURL& requesting_origin,
-                                                const GURL& embedding_origin) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  // This is required because constant permissions don't have a
-  // ContentSettingsType.
-  if (IsConstantPermission(permission))
-    return;
-
-  HostContentSettingsMapFactory::GetForProfile(profile_)->UpdateLastUsage(
-      requesting_origin,
-      embedding_origin,
-      PermissionTypeToContentSetting(permission));
-}
-
 int PermissionManager::SubscribePermissionStatusChange(
     PermissionType permission,
     const GURL& requesting_origin,