Remove ImageObserver::AnimationAdvanced

This is only called from test-code, and thus is dead in practice.
Replace uses in test-code with the the Changed() method.

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I9cdf92314140e65c30bc2a901d34345bf128392d
Reviewed-on: https://chromium-review.googlesource.com/c/1286813
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#600538}
7 files changed