Ash Tray: Rename ManagedDeviceView to ManagedDeviceTrayItemView.

This rename clears up the ambiguity between the managed device icon shown in the tray and the
managed device row in the tray bubble.

BUG=921267

Change-Id: I42476544dde50260d835371cd9ef59d9f20e7616
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1670062
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Reviewed-by: Tim Song <tengs@chromium.org>
Commit-Queue: Tim Song <tengs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672291}
5 files changed