code: function validateAttributeValue(className, value, updateFn) {
      var origValue;
  
      if (!needsInterpolation(value)) {
        switch (className.replace(SUFFIXES,"")) {
          case 'layout'        :
            if (!findIn(value, LAYOUT_OPTIONS)) {
              value = LAYOUT_OPTIONS[0];    // 'row';
            }
            break;
  
          case 'flex'          :
            if (!findIn(value, FLEX_OPTIONS)) {
              if (isNaN(value)) {
                value = '';
              }
            }
            break;
  
          case 'flex-offset' :
          case 'flex-order'    :
            if (!value || isNaN(+value)) {
              value = '0';
            }
            break;
  
          case 'layout-align'  :
            var axis = extractAlignAxis(value);
            value = $mdUtil.supplant("{main}-{cross}",axis);
            break;
  
          case 'layout-padding' :
          case 'layout-margin'  :
          case 'layout-fill'    :
          case 'layout-wrap'    :
          case 'layout-nowrap' :
            value = '';
            break;
        }
  
        if (value != origValue) {
          (updateFn || angular.noop)(value);
        }
      }
  
      return value ? value.trim() : "";
    }
docs: For the Layout attribute value, validate or replace with default
  fallback value