Introduce url_list to the Response scheme of CacheStorage.

content/browser/cache_storage/cache_storage.proto

 // 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.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package content.proto;
 
@@ skipping 23 matching lines @@
     DEFAULT_TYPE = 2;
     ERROR_TYPE = 3;
     OPAQUE_TYPE = 4;
     OPAQUE_REDIRECT_TYPE = 5;
   }
 
   required int32 status_code = 1;
   required string status_text = 2;
   required ResponseType response_type = 3;
   repeated CacheHeaderMap headers = 4;
-  optional string url = 5;
+  optional string url = 5 [deprecated = true];
   optional int64 response_time = 6;
   repeated string cors_exposed_header_names = 7;
+  repeated string url_list = 8;
 }
 
 message CacheMetadata {
   required CacheRequest request = 1;
   required CacheResponse response = 2;
   optional int64 entry_time = 3;
 }