demo-image-el.html

<link rel="import" href="../polymer/polymer.html">

<!-- this is a demo element that is being rendered by row-adder element -->
<dom-module id="demo-image-el">
    <style>
        :host {
            display: block;
            margin: 0;
            padding: 50px;
        }
        img {
            height: 100%;
            width: 100%;
        }
    </style>
    <template>
        <img src$="[[src]]" alt$="[[alt]]" is-content="attr" content-id="image-url" content-attr="src, alt">
    </template>
    <script>
        Polymer({
            is: 'demo-image-el',

            properties: {
                src: {
                    type: String,
                    value: '',
                    reflectToAttribute: true,
                    notify: true
                },

                alt: {
                    type: String,
                    value: '',
                    notify: true
                },

                usercontent: {
                    type: Object,
                    notify: true,
                    reflectToAttribute: false
                }
            },

            behaviors: [
                ContentEditorBehavior
            ],
        });
    </script>
</dom-module>