Enable outdated plugin infobars even when third-party plugin installation is not enabled.

Even built-in plugins can be outdated, in particular if plugin metadata is updated separately from a Chrome update.

This change moves logic for dealing with out-of-date plugins out from the ENABLE_PLUGIN_INSTALLATION build flag, which then is completely dead and is therefore removed.

BUG=509832

Review-Url: https://codereview.chromium.org/1242463002
Cr-Commit-Position: refs/heads/master@{#456456}
32 files changed