GitLab

https://codereview.chromium.org/505373002 introduced a regression by
implicitly changing an Update() call to an UpdatePageActions() call on
extensions being loaded/unloaded. This is mostly correct, but we lost the
check to make sure an extension didn't override the bookmark star. Correct this.
Also add a regression test.

BUG=410372
TBR=sky@chromium.org (minor TestBrowserWindow change)

Review URL: https://codereview.chromium.org/540483002

Cr-Commit-Position: refs/heads/master@{#293737}