Convert TrayAccessibility to wm common types
* Move //ui/chromeos/accessibility_types.h into //ash/common because it is
used in non-chromeos code, but only in //ash.
* Migrate AccessibilityObserver to WmSystemTrayNotifier
* Move AccessibilityObserver to its own file to reduce the #include burden of
wm_system_tray_notifier.h
* Fix include-what-you-use violations
I will move tray_accessibility.* into //ash/common in a separate CL because it
will involve moving tray_details_view.h, which is widely used.
BUG=619636,621574
TEST=ash_unittests
TBR=atwilson@chromium.org for mechanical change to //chrome/browser/policy
Review-Url: https://codereview.chromium.org/2074913005
Cr-Commit-Position: refs/heads/master@{#400791}
37 files changed
