dev@101: <button md-icon-button (click)="emitPlayPause()">
dev@32:   <md-icon>
dev@236:     <ng-template [ngIf]="isPlaying()">pause</ng-template>
dev@236:     <ng-template [ngIf]="!isPlaying()">play_arrow</ng-template>
dev@32:   </md-icon>
dev@27: </button>