framework/ember/app/views/discussions/index.js

import Ember from 'ember';

export default Ember.View.extend({
    _updateTitle: function() {
        var q = this.get('controller.searchQuery');
        this.get('controller.controllers.application').set('pageTitle', q ? '"'+q+'"' : '');
    }.observes('controller.searchQuery'),

    didInsertElement: function() {
        this._updateTitle();
    }
});