GitLab

Cast extensions and embedded frames should not navigate by default.

Bug: internal b/74124275
Bug: internal b/112805642

Test: Try to navigate extension page, verify the navigation is blocked.
Change-Id: I84174d9ed2d48038edfef0fcb17511694dbdbe3c
Reviewed-on: https://chromium-review.googlesource.com/1212344Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Sean Topping <seantopping@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589591}