Include all server redirects in referrer chain

chrome/common/safe_browsing/csd.proto

 // Copyright (c) 2012 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.
 //
 // This proto file includes:
 // (1) Client side phishing and malware detection request and response
 //   protocol buffers.  Those protocol messages should be kept in sync
 //   with the server implementation.
 //
 // (2) Safe Browsing reporting protocol buffers.
@@ skipping 398 matching lines @@
   // Referrer url of this entry.
   optional string referrer_url = 4;
 
   // Main frame URL of referrer.
   optional string referrer_main_frame_url = 5;
 
   // If this URL loads in a different tab/frame from previous one.
   optional bool is_retargeting = 6;
 
   optional double navigation_time_msec = 7;
+
+  // Set only if server redirects happen in navigation.
+  // The first entry in |server_redirect_chain| should be the original request

[Nathan Parker, 2017/01/20 23:36:20]

Looks like the last entry would be redundant, but if auk et.al would prefer it
that way, fine with me.

[Jialiu Lin, 2017/01/21 00:48:27]

I think it is less confusing in this way. auk and others didn't object when I
made change in the csd_client.proto. 

+  // url, and the last entry should be the same as |url|.
+  repeated string server_redirect_chain = 8;
 }  // End of URLChainEntry
 
 message ClientDownloadResponse {
   enum Verdict {
     // Download is considered safe.
     SAFE = 0;
     // Download is considered dangerous.  Chrome should show a warning to the
     // user.
     DANGEROUS = 1;
     // Download is uncommon.  Chrome should display a less severe warning.
@@ skipping 399 matching lines @@
   optional bool did_proceed = 8;
 
   // Whether user visited this origin before.
   optional bool repeat_visit = 9;
 
   // The same token in ClientDownloadResponse. This field is only set if its
   // report type is DANGEROUS_DOWNLOAD_RECOVERY, DANGEROUS_DOWNLOAD_WARNING or
   // DANGEROUS_DOWNLOAD_BY_API.
   optional bytes token = 15;
 }