Remove --install-from-webstore and --limited-install-from-webstore
Both these switches should be removed, as they allow malware
to potentially install extensions on a user's computer.
Since the --install-from-webstore switch is also being used
to install ephemeral apps, rename it to
--install-ephemeral-app-from-webstore, and ensure that this
only works on installed ephemeral apps on Windows. (This
has sufficient checks in place, such as an extension of
the same ID already being installed, that this is safe.)
BUG=410833
Review URL: https://codereview.chromium.org/
617833003
Cr-Commit-Position: refs/heads/master@{#297868}