Project core and plugins actions exposing label and title. Label
supposed to be used as button name and title is supposed to be used
as button tooltip. Support for tooltip is added in this change. To make
minimal invasive change, we preserve title that was already taken as the
name of the button and add new tooltip attribute.
Alternative approach would be to consistently use label and title, like
it is done on change screen. However that approach may break some users,
that rely on current naming convention.
Note that this also fixed the problem for plugin authors. For example in
custom element in project screen, tooltip can be used as following:
<gr-repo-command
title="[[action.label]]"
tooltip="[[action.title]]"
on-command-tap="_handleCommandTap">
</gr-repo-command>
Bug: Issue 9638
Change-Id: Ib1b54eb7cd4ba544402d293b9fce9bb176b01065
aa04f13bdf