[TopAppBar] Icon buttons in Card have the class mdc-icon-button while the buttons in Top App Bar don't

[tychenjiajun]

It's strange and confusing.
Card

<div class="mdc-card__action-icons">
   <button class="material-icons mdc-icon-button mdc-card__action mdc-card__action--icon" title="Share">share</button>
    <button class="material-icons mdc-icon-button mdc-card__action mdc-card__action--icon" title="More options">more_vert</button>
  </div>

Top App Bar

<section class="mdc-top-app-bar__section mdc-top-app-bar__section--align-end" role="toolbar">
      <a href="#" class="material-icons mdc-top-app-bar__action-item" aria-label="Download" alt="Download">file_download</a>
      <a href="#" class="material-icons mdc-top-app-bar__action-item" aria-label="Print this page" alt="Print this page">print</a>
      <a href="#" class="material-icons mdc-top-app-bar__action-item" aria-label="Bookmark this page" alt="Bookmark this page">bookmark</a>
    </section>

[moog16]

@tychenjiajun the Card is just a wrapper component, which means we didn't build in icon styles. This means we have to use mdc-icon-button in the Card.

However looking at @mixin mdc-top-app-bar-icon_ is very similar to the @mixin mdc-icon-button-base_. And this might be a good opprotunity to combine the 2 mixins and use mdc-icon-button instead and remove the mdc-top-app-bar-icon mixin. I will wait for others on the team to chime in.

[moog16]

We will look into making top app bar support icon button, and possibly deprecate the mdc-top-app-bar-icon_ mixin in the future.

[moog16]

Closing. Merged #4745