Restrict use of two app-launching command line flags

Mitigate abuse of the load-and-launch-app and load-apps flags by
disallowing loading of non-app extensions from these flags.

For the official build, the flags no-op instead of showing an error popup
to avoid giving users with hijacked shortcuts a bad time (the error
message is shown then Chrome shuts down)

Rollforward of https://codereview.chromium.org/2180853004/

BUG=624098

Committed: https://crrev.com/93c60cd3ef5908984e173112dc09345bb5714036
Cr-Commit-Position: refs/heads/master@{#407824}

patch from issue 2108853002 at patchset 140001 (http://crrev.com/2108853002#ps140001)

Review-Url: https://codereview.chromium.org/2177383005
Cr-Commit-Position: refs/heads/master@{#409870}
6 files changed