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This is a clean-up CL which moves all of the LocalInputMonitor
related classes into their own folder and provides a public header
and lib for usage by the rest of the host classes.

Change-Id: I0a9ced94750d0724f99dace24c991fd3194eebb4
Reviewed-on: https://chromium-review.googlesource.com/1185298
Commit-Queue: Joe Downing <joedow@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585928}