I plan to use GlobalRequestID (https://cs.chromium.org/chromium/src/content/public/browser/global_request_id.h?q=GlobalRequest+package:%5Echromium$&l=13), which is a pair of ints. This will also be the same ID for any redirects in the redirect chain.

I'd suggest we add a GlobalRequestID object to the proto that is a pair of int32s and the directive would look like PageID=x-y or similar.

sgtm.

I've decided to generate ID's in DataReductionProxyNetworkDelegate instead. GlobalRequestID is somewhat confusing (plzNavigate vs non-plzNavigate) and there is a possible privacy issue with reporting any information not related to data saver.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dba8a17e64a4d6bc35e941b2b2a46003c25c5505

commit dba8a17e64a4d6bc35e941b2b2a46003c25c5505
Author: ryansturm <ryansturm@chromium.org>
Date: Tue Apr 11 00:43:58 2017

Adding a data saver page id to requests and reports

This adds a page id determined from GlobalRequestID to main frame data
saver requests as well as PageLoad Metrics pingback reports.

BUG= 701579 

Review-Url: https://codereview.chromium.org/2803813003
Cr-Commit-Position: refs/heads/master@{#463470}

[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_data.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_data.h
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_data_unittest.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate_unittest.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client_unittest.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options.h
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/core/browser/data_reduction_proxy_request_options_unittest.cc
[modify] https://crrev.com/dba8a17e64a4d6bc35e941b2b2a46003c25c5505/components/data_reduction_proxy/proto/pageload_metrics.proto

 Issue 701512  has been merged into this issue.