MacViewsBrowser: Link in nsmenuitem_additions.mm
MacViewsBrowser: Link in nsmenuitem_additions.mm

Code under chrome::IsChromeAccelerator() calls [NSMenuItem
cr_firesForKeyEventIfEnabled:] assuming it's always linked in. Currently
for mac_views_browser=1 it's not.

The call can be triggered by some extension installs/upgrades while
verifying whether an extension key binding is valid.

BUG=516242

Review URL: https://codereview.chromium.org/1267043003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#341657}

ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend