Merge UnifiedDetailedViewDelegate w/ parent class.

This CL merges UnifiedDetailedViewDelegate with its parent class,
DetailedViewDelegate. Previously, there was a DetailedViewDelegate for
old SystemTray, but the old one is now removed.

TEST=trybot pass
BUG=901713

Change-Id: Ibd4aa0d6e09fc6fb0b8ee452e6dc6e2c8a6baa37
Reviewed-on: https://chromium-review.googlesource.com/c/1414810
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623557}
15 files changed