Improves application state persistance.

chrome/browser/resources/print_preview/data/margins.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('print_preview', function() {
   'use strict';
 
   /**
    * Creates a Margins object that holds four margin values in points.
    * @param {number} top The top margin in pts.
@@ skipping 12 matching lines @@
     this.value_ = {};
     this.value_[print_preview.ticket_items.CustomMargins.Orientation.TOP] = top;
     this.value_[print_preview.ticket_items.CustomMargins.Orientation.RIGHT] =
         right;
     this.value_[print_preview.ticket_items.CustomMargins.Orientation.BOTTOM] =
         bottom;
     this.value_[print_preview.ticket_items.CustomMargins.Orientation.LEFT] =
         left;
   };
 
+  /**
+   * Parses a margins object from the given serialized state.
+   * @param {Object} state Serialized representation of the margins created by
+   *     the {@code serialize} method.
+   * @return {!print_preview.Margins} New margins instance.
+   */
+  Margins.parse = function(state) {
+    return new print_preview.Margins(
+        state[print_preview.ticket_items.CustomMargins.Orientation.TOP],
+        state[print_preview.ticket_items.CustomMargins.Orientation.RIGHT],
+        state[print_preview.ticket_items.CustomMargins.Orientation.BOTTOM],
+        state[print_preview.ticket_items.CustomMargins.Orientation.LEFT]);
+  };
+
   Margins.prototype = {
     /**
      * @param {!print_preview.ticket_items.CustomMargins.Orientation}
      *     orientation Specifies the margin value to get.
      * @return {number} Value of the margin of the given orientation.
      */
     get: function(orientation) {
       return this.value_[orientation];
     },
 
     /**
      * @param {!print_preview.ticket_items.CustomMargins.Orientation}
      *     orientation Specifies the margin to set.
      * @param {number} value Updated value of the margin in points to modify.
      * @return {!print_preview.Margins} A new copy of |this| with the
      *     modification made to the specified margin.
      */
     set: function(orientation, value) {
-      var newValue = {};
-      for (var o in this.value_) {
-        newValue[o] = this.value_[o];
-      }
+      var newValue = this.clone_();
       newValue[orientation] = value;
       return new Margins(
           newValue[print_preview.ticket_items.CustomMargins.Orientation.TOP],
           newValue[print_preview.ticket_items.CustomMargins.Orientation.RIGHT],
           newValue[print_preview.ticket_items.CustomMargins.Orientation.BOTTOM],
           newValue[print_preview.ticket_items.CustomMargins.Orientation.LEFT]);
     },
 
     /**
      * @param {print_preview.Margins} other The other margins object to compare
      *     against.
      * @return {boolean} Whether this margins object is equal to another.
      */
     equals: function(other) {
       if (other == null) {
         return false;
       }
       for (var orientation in this.value_) {
         if (this.value_[orientation] != other.value_[orientation]) {
           return false;
         }
       }
       return true;
+    },
+
+    /** @return {Object} A serialized representation of the margins. */
+    serialize: function() {
+      return this.clone_();
+    },
+
+    /**
+     * @return {Object} Cloned state of the margins.
+     * @private
+     */
+    clone_: function() {
+      var clone = {};
+      for (var o in this.value_) {
+        clone[o] = this.value_[o];
+      }
+      return clone;
     }
   };
 
   // Export
   return {
     Margins: Margins
   };
 });