add option for original domain

proto/dom_distiller.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";
 
 package dom_distiller.proto;
 option optimize_for = LITE_RUNTIME;
 option java_package = "com.dom_distiller.proto";
 option java_outer_classname = "DomDistillerProtos";
@@ skipping 67 matching lines @@
 message DomDistillerOptions {
   // Whether to extract only the text (or to include the containing html).
   optional bool extract_text_only = 1;
 
   // How much debug output to dump to window.console.
   // (0): Logs nothing
   // (1): Text Node data for each stage of processing
   // (2): (1) and some node visibility information
   // (3): (2) and extracted paging information
   optional int32 debug_level = 2;
+
+  // The original domain of the page if it's a file://, used for detecting next/prev page links
+  // which expects the same domain for both current page and paging links.
+  optional string original_domain = 3;
 }