Move the accessibility mode flags from content/ to ui/

In order to use the accessibility mode flags from the ui AXPlatformNode
and friends, we need to move the flags from content/common into
ui/accessibility. The majority of this change is mechincal renaming.

Bug: 703369
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_site_isolation
Change-Id: I683d1e0abcf5ce33b65ea206f07899a12a284bb5
Reviewed-on: https://chromium-review.googlesource.com/588383
Commit-Queue: Doug Turner <dougt@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490630}
49 files changed