content: Fix reponse -> response typos in comments

Bug: none
Change-Id: I2014adfa408153e801a5c5b94423e63ecb08c48b
Reviewed-on: https://chromium-review.googlesource.com/579191


Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: Nasko Oskov <nasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488318}