GitLab

This is a follow-up to https://crrev.com/c/2347371 which is a mechanical
move of ThreadedInputHandler into its own separate file. There are no
changes from the previous CL.

Bug: 915926
Change-Id: I58e6a82271cb81cd5e9dd906a61808d8486b6cb2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2347924
Commit-Queue: David Bokan <bokan@chromium.org>
Reviewed-by: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796987}