Print preview page selection should not require a rerendering of draft pages.

chrome/browser/resources/print_preview/page_settings.js

 // Copyright (c) 2011 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 PageSettings object. This object encapsulates all settings and
    * logic related to page selection.
@@ skipping 159 matching lines @@
           this.previouslySelectedPages_.push(i + 1);
       }
 
       if (!this.isPageSelectionValid())
         this.onSelectedPagesTextfieldChanged();
     },
 
     /**
      * Updates |this.previouslySelectedPages_| with the currently selected
      * pages.
-     * @private
      */
-    updatePageSelection_: function() {
+    updatePageSelection: function() {
       this.previouslySelectedPages_ = this.selectedPagesSet;
     },
 
     /**
      * @private
      * @return {boolean} true if currently selected pages differ from
      *     |this.previouslySelectesPages_|.
      */
     hasPageSelectionChanged_: function() {
       return !areArraysEqual(this.previouslySelectedPages_,
                              this.selectedPagesSet);
     },
 
     /**
+     * Checks if the page selection has changed and is valid.
+     * @return {boolean} true if the page selection is changed and is valid.
+     */
+    hasPageSelectionChangedAndIsValid: function() {
+      return this.isPageSelectionValid() && this.hasPageSelectionChanged_();
+    },
+
+    /**
      * Validates the contents of |this.selectedPagesTextfield|.
      *
      * @return {boolean} true if the text is valid.
      */
     isPageSelectionValid: function() {
       if (this.allPagesRadioButton_.checked ||
           this.selectedPagesText.length == 0) {
         return true;
       }
       return isPageRangeTextValid(this.selectedPagesText, this.totalPageCount_);
     },
 
     /**
      * Checks all page selection related settings and requests a new print
      * previw if needed.
      * @return {boolean} true if a new preview was requested.
      */
     requestPrintPreviewIfNeeded: function() {
-      if (this.isPageSelectionValid() && this.hasPageSelectionChanged_()) {
-        this.updatePageSelection_();
+      if (this.hasPageSelectionChangedAndIsValid()) {
+        this.updatePageSelection();
         requestPrintPreview();
         return true;
       }
       if (!this.isPageSelectionValid())
         this.onSelectedPagesTextfieldChanged();
       return false;
     },
 
     /**
      * Validates the selected pages and updates the hint accordingly.
@@ skipping 40 matching lines @@
         this.onSelectedPagesTextfieldChanged();
 
       // Toggling between "all pages"/"some pages" radio buttons while having an
       // invalid entry in the page selection textfield still requires updating
       // the print summary and print button.
       if (!this.isPageSelectionValid() || !this.hasPageSelectionChanged_()) {
         cr.dispatchSimpleEvent(document, 'updateSummary');
         cr.dispatchSimpleEvent(document, 'updatePrintButton');
         return;
       }
-      this.previouslySelectedPages_ = this.selectedPagesSet;
       requestPrintPreview();
     },
 
     /**
      * Whenever |this.selectedPagesTextfield| gains focus we add a timer to
      * detect when the user stops typing in order to update the print preview.
      * @private
      */
     addTimerToSelectedPagesTextfield_: function() {
       this.timerId_ = window.setTimeout(
@@ skipping 82 matching lines @@
           this.onSelectedPagesMayHaveChanged_();
         }
       }.bind(this);
     }
   };
 
   return {
     PageSettings: PageSettings,
   };
 });