[ozone/wayland] Split WaylandKeyboard::Key in two smaller methods

This CL is a driven-by CL that splits the existing WaylandKeyboard::Key
method into two smaller ones.

In practice, it brings no functionality change, but makes it
easier to understand follow up changes like https://crrev.com/c/874670.

BUG=578890

Change-Id: If62cd7158cec4af338af2eb17a9399624d84d5f5
Reviewed-on: https://chromium-review.googlesource.com/878481
Reviewed-by: Michael Spang <spang@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#530914}
2 files changed