Change print setting conventions for margins to support more options.

chrome/browser/resources/print_preview/margin_settings.js

Index: chrome/browser/resources/print_preview/margin_settings.js
diff --git a/chrome/browser/resources/print_preview/margin_settings.js b/chrome/browser/resources/print_preview/margin_settings.js
index 5f48ed79436849ad7b99a61aa0332341f76dacc6..dfeac4abd3a31fb741ecfafb2330117b78975f1f 100644
--- a/chrome/browser/resources/print_preview/margin_settings.js
+++ b/chrome/browser/resources/print_preview/margin_settings.js
@@ -179,6 +179,20 @@ cr.define('print_preview', function() {
     },
 
     /**
+     * Gets the string representation of the margin type selected.
+     *
+     * @return {string}
+     */
+    get selectedMarginsAsString() {
+      if (this.isNoMarginsSelected())
+        return "noMargins";
+      else if (this.isCustomMarginsSelected())
+        return "customMargins";
+      else
+        return "defaultMargins";
+    },
+
+    /**
      * @return {boolean} True if default margins are selected.
      */
     isDefaultMarginsSelected: function() {