[Activity log] Rework extraction of URLs from argument lists

chrome/browser/extensions/activity_log/activity_action_constants.cc

 // Copyright 2013 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.
 
 // String constants used when logging data in the extension activity log.
 
 #include "chrome/browser/extensions/activity_log/activity_action_constants.h"
 
 namespace activity_log_constants {
 
 // Keys that may be used in the "other" attribute of an Action.
 const char kActionBlockedReason[] = "blocked_reason";
 const char kActionDomVerb[] = "dom_verb";
 const char kActionExtra[] = "extra";
 const char kActionPrerender[] = "prerender";
 const char kActionWebRequest[] = "web_request";
 
 // A string used in place of the real URL when the URL is hidden because it is
 // in an incognito window.  Extension activity logs mentioning kIncognitoUrl
 // let the user know that an extension is manipulating incognito tabs without
 // recording specific data about the pages.
 const char kIncognitoUrl[] = "<incognito>";
 
+// A string used as a placeholder for URLs which have been removed from the
+// argument list and stored to the arg_url field.
+const char kArgUrlPlaceholder[] = "<arg_url>";
+
 }  // namespace activity_log_constants