Remove most PlzNavigate mentions in content/

This CL removes most of the references to PlzNavigate in the comments of
content/. Some problematic cases where further expertise is needed are
left out, but this covers more than 90% of the references.

Change-Id: I6e060a5a92afe6ad3e078e3e5351020e4a85565f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1729082
Commit-Queue: Arthur Hemery <[email protected]>
Reviewed-by: Nasko Oskov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#683162}
41 files changed