A check will fail if the context passed in is not a native context.
Change the code to get the native context from the passed context.

Bug: chromium:804288
Change-Id: Iad314a3dd170355cf524b9230a692a6329564f8a
Reviewed-on: https://chromium-review.googlesource.com/878324Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50761}