EXO: Refactor pointer_gestures interface

Move pointer_gestures interface out of server.cc
This CL only moves code around.

Bug: 896710
Test: Built on ChromeOS
Change-Id: I5f33889794bc1ff3645f6bb0006fd9b8c87de5df
Reviewed-on: https://chromium-review.googlesource.com/c/1324146
Commit-Queue: Daniel Nicoara <dnicoara@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609392}
4 files changed