title: Angular Material Autocomplete MatAutocompleteTrigger
body: <p>Can someone please explain to me how does the <code>MatAutocompleteTrigger</code> work?</p>
  
  <pre><code>@ViewChild('autocompleteInput', { read: MatAutocompleteTrigger }) triggerAutocompleteInput: MatAutocompleteTrigger;
  
  &lt;mat-form-field&gt;
    &lt;input
      #autocompleteInput
      matInput
      placeholder="Label"
      formControlName="label"
      [matAutocomplete]="autocompletePanel"
    &gt;
  &lt;/mat-form-field&gt;
  
  &lt;mat-autocomplete #autocompletePanel="matAutocomplete" [displayWith]="displayFn"&gt;
    &lt;mat-option
      *ngFor="let item of items | async"
      [value]="item.label"
    &gt;
      {{ item.label }}
    &lt;/mat-option&gt;
  &lt;/mat-autocomplete&gt;
  
  this.triggerAutocompleteInput.optionSelections.subscribe(option =&gt; {
        console.log('Im gonna kill myself', option );
      });
  </code></pre>
  
  <p>It doesn't do anything. I can be selecting options all day long and nothing will fire. <strong>Shouldn't the subscription receive data when I click some option?</strong> The <code>this.triggerAutocompleteInput.panelClosingActions</code> works only when you have the autocomplete panel active and you close it with blur.</p>
  
  <p>I don't understand the behavior and I don't understand the documentation.</p>
  
  <p><strong>And what about if you need to access the input through <code>nativeElement</code>?</strong> You can't do it when you use it as <code>MatAutocompleteTrigger</code> as far as I can tell.</p>
  
  <p>I'm going crazy.</p>