Use ATK_ROLE_APPLICATION for toplevel applications

The accessibility code for Aura on Linux was using the ATK_ROLE_EMBEDDED
role for elements with the role ax::mojom::Role::kApplication so that
it would not apply to ARIA applications. To be consistent with other
applications, ATK_ROLE_APPLICATION is more appropriate. We only use this
when the element is the root of the accessibility tree.

TEST=accessibility_unittests --gtest_filter=AXPlatformNodeAuraLinuxTest.*

Bug: 867006
Change-Id: I6c64b142cf3307c906f73235ed8247e828cd2394
Reviewed-on: https://chromium-review.googlesource.com/1148397
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577920}
2 files changed