chromeos: really fix up event locations

I had the locations wrong. The root is reset to the local, not the
local to the root. Not sure why some tests passed with the other way.

BUG=792214
TEST=none

Change-Id: I9a0a29c0c412d9c097d1c7df64312e1693328998
Reviewed-on: https://chromium-review.googlesource.com/810009Reviewed-by: Elliot Glaysher <erg@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521950}

ui/aura/event_injector.cc

@@ -51,8 +51,8 @@ ui::EventDispatchDetails EventInjector::Inject(WindowTreeHost* host,
     // root location. The non-ui-service code does this by way of
     // OnEventFromSource() ending up in LocatedEvent::UpdateForRootTransform(),
     // which reset the root_location to match the location.
-    event->AsLocatedEvent()->set_location_f(
-        event->AsLocatedEvent()->root_location_f());
+    event->AsLocatedEvent()->set_root_location_f(
+        event->AsLocatedEvent()->location_f());
   }
 
   if (!remote_event_dispatcher_) {