GitLab

Only Mac needs to know about surface activations, so avoid sending
OnFirstSurfaceActivation on other platforms.

Bug: 893731
Change-Id: Id5de1043d0c432964c1897af50440bf02277506f
Reviewed-on: https://chromium-review.googlesource.com/c/1286354
Commit-Queue: Saman Sami <samans@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601322}