src/xblocks/block.js
function (content) {
            content = trim(content);

            if (this.mounted) {
                invoke(this, [ Constants.BLOCK, 'setMountedContent' ], content);

            } else {
                dom.contentNode(this).innerHTML = content;
                this.upgrade();
            }
        }
function (content) {
            content = trim(content);

            if (this.mounted) {
                invoke(this, [ Constants.BLOCK, 'setMountedContent' ], content);

            } else {
                dom.contentNode(this).innerHTML = content;
                this.upgrade();
            }
        }
Installing a new content.
@param {string} content