drubery@ -- do you want to own this?
If so, please assign to yourself and add SafeBrowsing-Triaged

Sure, I can take this.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d9c7cf1b1235f7a3be1e1cc071536923be0f65f1

commit d9c7cf1b1235f7a3be1e1cc071536923be0f65f1
Author: Daniel Rubery <drubery@chromium.org>
Date: Mon Sep 10 22:57:13 2018

Fix at() usage for safe_browsing code

In some cases, vec->at(i) was used as a more-readable alternative to
(*vec)[i]. In others, it was used for const access to maps. at has
questionable interactions with exceptions (see
https://groups.google.com/a/chromium.org/forum/#!msg/cxx/6TDgM5g-NH4/NJSmyU01BgAJ),
so I've added (*vec)[i] where possible, and bounds checked everywhere.


Bug:  881604 
Change-Id: Ia38ec235a8264a54ddc0dbe570c79e0227fe0f9e
Reviewed-on: https://chromium-review.googlesource.com/1217104
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590099}
[modify] https://crrev.com/d9c7cf1b1235f7a3be1e1cc071536923be0f65f1/chrome/browser/safe_browsing/safe_browsing_blocking_page_test.cc
[modify] https://crrev.com/d9c7cf1b1235f7a3be1e1cc071536923be0f65f1/chrome/browser/safe_browsing/safe_browsing_navigation_observer_browsertest.cc
[modify] https://crrev.com/d9c7cf1b1235f7a3be1e1cc071536923be0f65f1/chrome/browser/safe_browsing/safe_browsing_navigation_observer_unittest.cc
[modify] https://crrev.com/d9c7cf1b1235f7a3be1e1cc071536923be0f65f1/components/safe_browsing/triggers/trigger_manager_unittest.cc
[modify] https://crrev.com/d9c7cf1b1235f7a3be1e1cc071536923be0f65f1/components/safe_browsing/triggers/trigger_throttler.cc