The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e5145ec87164071c146a3cddeaf5c6dcfbcebd54

commit e5145ec87164071c146a3cddeaf5c6dcfbcebd54
Author: Tarun Bansal <tbansal@chromium.org>
Date: Tue Oct 09 17:57:45 2018

Send interventions header when triggering resource loading hints

Add logic to send interventions header when
resource loading hints intervention is triggered.
This is a temporary solution required until Previews
interventions are reported via Reporting API:
https://developers.google.com/web/updates/2018/09/reportingapi#reportypes

Change-Id: I8853db58735d4ec172f86b2179f42f28168c2341
Bug:  891728 
Reviewed-on: https://chromium-review.googlesource.com/c/1267375
Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597985}
[modify] https://crrev.com/e5145ec87164071c146a3cddeaf5c6dcfbcebd54/chrome/browser/previews/resource_loading_hints/resource_loading_hints_browsertest.cc
[modify] https://crrev.com/e5145ec87164071c146a3cddeaf5c6dcfbcebd54/third_party/blink/renderer/core/loader/frame_fetch_context.cc