Sure that makes sense

Right now navigating to these two URLs opens the native page inside Chrome. If the user focuses the omnibox, doesn't notice the bottom nav and decides to type in a URL, I agree that we should leave Chrome Home open and go to one of the panels. This shouldn't be too hard to implement - we route everything through BottomSheet so we could put some checks in there before allowing the navigation to proceed.

That said, would we block stable launch on this? If not, can we please reprioritize?

Actually yes, right now it seems chrome://bookmarks is broken even on Stable so I'm down to de-pri

Broken on Stable how? Navigating to chrome://bookmarks in non-Chrome Home should open bookmarks as a native page inside the browser.

When I navigate to chrome://bookmarks in non-Chrome Home on Chrome Stable I see "This site can't be reached" ERR_INVALID_URL.

It looks like chrome://history is the only URL we redirect. I'm not sure if not redirecting was an intentional decision for bookmarks and downloads or an over sight.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1d68edb8418078172477b3ed535f79288156eccc

commit 1d68edb8418078172477b3ed535f79288156eccc
Author: Troy Hildebrandt <thildebr@chromium.org>
Date: Thu Oct 05 16:33:53 2017

[Home] Open chrome://bookmarks, downloads, and history in the sheet.

Bug:  755783 
Change-Id: I2c9e36d26e91b592a41ce94c1a6618ca3bceaea6
Reviewed-on: https://chromium-review.googlesource.com/690750
Reviewed-by: Theresa <twellington@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Troy Hildebrandt <thildebr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506757}
[modify] https://crrev.com/1d68edb8418078172477b3ed535f79288156eccc/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java

Works fine as per expected behavior, Verified on 63.0.3234.0
Navigating to chrome://bookmarks, downloads, and history  opens in the chrome- Home sheet it self.