The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1004a7a4a4f6aca1422caa28aa9e26741e6760f9

commit 1004a7a4a4f6aca1422caa28aa9e26741e6760f9
Author: Jialiu Lin <jialiul@chromium.org>
Date: Mon Jun 26 18:11:21 2017

Sanitize referrer chain in ClientDownloadRequest if it is a sampled
ping.

Also shorten all data url in referrer chain to save some bytes.

Bug:  726493 
Change-Id: I6b33ad6d9144ea2244922f254f2a1188249f0658
Reviewed-on: https://chromium-review.googlesource.com/530158
Commit-Queue: Jialiu Lin <jialiul@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Reviewed-by: Nathan Parker <nparker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#482322}
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/chrome/browser/safe_browsing/download_protection_service.cc
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/chrome/browser/safe_browsing/safe_browsing_navigation_observer_browsertest.cc
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.cc
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/chrome/browser/safe_browsing/safe_browsing_navigation_observer_manager.h
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/components/safe_browsing/common/BUILD.gn
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/components/safe_browsing/common/DEPS
[add] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/components/safe_browsing/common/utils.cc
[add] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/components/safe_browsing/common/utils.h
[modify] https://crrev.com/1004a7a4a4f6aca1422caa28aa9e26741e6760f9/components/safe_browsing/csd.proto