Updates the order of key mappings to match the same as layout rendering in VK.

The modifier importance priority is: Altgr > Shift > Capslock.
So if user presses a key with Shift + Altgr + Capslock and the key mapping is not defined for the input method.
It will fallback to other key mappings in this order:
 - Shift + Altgr
 - Altgr + Capslock
 - Shift + Capslock
 - Altgr
 - Shift
 - Capslock
 - Normal

Bug: 910049
Change-Id: I3a274ba02671977a075ee27441acf429cf4569cb
Reviewed-on: https://chromium-review.googlesource.com/c/1356735
Reviewed-by: Leo Zhang <googleo@chromium.org>
Commit-Queue: Leo Zhang <googleo@chromium.org>
Commit-Queue: Shu Chen <shuchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614628}
5 files changed