ozone: dri: Remove distinction between root_location and location

ozone: dri: Remove distinction between root_location and location

Aura expects these to be the same, so just use location() everywhere.

This shouldn't affect anything because although we were passing along
screen location inside root_location(), Event::UpdateForRootTransform
sets it back to the transformed location(). So no code actually saw our
screen location.

BUG=none
TEST=unit tests, manual on link_freon with 2 monitors

Committed: https://crrev.com/8019c703c77f9a689f1f3d4d6527167479e8bb9e
Cr-Commit-Position: refs/heads/master@{#308149}

[spang, 2014-12-05 22:57:37]

spang@chromium.org changed reviewers:
+ sadrul@chromium.org

[sadrul, 2014-12-11 14:59:55]

lgtm

[spang, 2014-12-12 18:47:47]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2014-12-12 18:48:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/766833003/1

[commit-bot: I haz the power, 2014-12-12 20:17:58]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-12 20:18:47]

Patchset 1 (id:??) landed as
https://crrev.com/8019c703c77f9a689f1f3d4d6527167479e8bb9e
Cr-Commit-Position: refs/heads/master@{#308149}