elawrence@ are you the right owner for this?

 Issue 739480  is basically the same root cause.

 Issue 739480  is tracking the iOS change; we'll fix Android with this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/46acd92a027cb16279fcf72e5eeaebc5da92d64b

commit 46acd92a027cb16279fcf72e5eeaebc5da92d64b
Author: Eric Lawrence <elawrence@chromium.org>
Date: Fri Jul 14 00:55:20 2017

Treat chrome-native scheme as Secure

chrome-native: is a scheme used for placeholder navigations that allow
UIs to be drawn with platform native widgets instead of HTML. The scheme
should be treated as 'secure' because they entirely in the browser, so
there is no danger of manipulation or eavesdropping by third parties,
and we do not wish to trigger the Non Secure warnings that are landing
with the HTTPBad Phase 2 feature.

BUG= 734581 
TEST=unit_tests --gtest_filter=ChromeContentClientTest.AdditionalSchemes

Change-Id: I8ccddfae8d06b2035099e3e7b13ac237d81464ef
Reviewed-on: https://chromium-review.googlesource.com/570538
Reviewed-by: Chris Palmer <palmer@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Eric Lawrence <elawrence@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486556}
[modify] https://crrev.com/46acd92a027cb16279fcf72e5eeaebc5da92d64b/chrome/common/chrome_content_client.cc
[modify] https://crrev.com/46acd92a027cb16279fcf72e5eeaebc5da92d64b/chrome/common/chrome_content_client_unittest.cc

commit 46acd92a027cb16279fcf72e5eeae was:
  initially in 61.0.3157.0