GitLab

Added a new function to initialize a descriptor panel, which includes
create a new panel object and binding click actions.

Changed unnecessary id attribute to class.

Bug: 928923
Change-Id: Ic352befdc512738bad5928485e3c4c048e09f263
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1639739Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Nancy Li <nancyly@google.com>
Cr-Commit-Position: refs/heads/master@{#666186}