Material Toolbar - Right Align Username

.fill-space {
  // This fills the remaining space, by using flexbox.
  // Every toolbar row uses a flexbox row layout.
  flex: 1 1 auto;
}

<md-toolbar color="primary">
  <span>Application Title</span>

  <!-- This fills the remaining space of the current row -->
  <span class="fill-space"></span>

  <span>Right Aligned Text</span>
</md-toolbar>