[Print Preview]: Added code to support pdf fit to page functionality.

chrome/browser/resources/print_preview/fit_to_page_settings.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 |FitToPageSettings| object. This object encapsulates all
+   * settings and logic related to the fit to page checkbox.
+   * @constructor
+   */
+  function FitToPageSettings() {
+    // @type {HTMLDivElement} This represents fit to page div element.
+    this.fitToPageOption_ = $('fit-to-page-option');
+
+    // @type {HTMLInputElement} This represents fit to page input element.
+    this.fitToPageCheckbox_ = $('fit-to-page');
+
+    // @type {boolean} True if fit to page option applies for the selected
+    //      user options. Fit to Page options applies only if we are previewing
+    //      a PDF and the current destination printer is actually a physcial
+    //      printer.
+    this.fitToPageApplies_ = true;
+
+    this.addEventListeners_();
+  }
+
+  cr.addSingletonGetter(FitToPageSettings);
+
+  FitToPageSettings.prototype = {
+    /**
+     * Checks whether the fit to page checkbox is checked or not.
+     * @return {boolean} true if Fit to page is checked.
+     */
+    hasFitToPage: function() {
+      return !previewModifiable && this.fitToPageCheckbox_.checked;
+    },
+
+    /**
+     * Updates |this.fitToPageApplies_| depending on the selected printer and
+     * preview data source type.
+     * @param {!string} printerName Selected printer name.
+     * @private
+     */
+    resetState_: function(printerName) {
+      if (!previewModifiable)
+        isPrintReadyMetafileReady = false;
+      var printToPDF = printerName == PRINT_TO_PDF;
+      this.fitToPageApplies_ = !previewModifiable && !printToPDF;
+    },
+
+    /**
+     * Uncheck the fit to page option when print scaling is disabled for the
+     * preview source plugin.
+     */
+    printScalingDisabledUpdateState: function() {

[dpapad, 2012/04/19 21:11:29]

Nit:
The naming of this function describes why it is called, not what it is doing,
this seems a bit weird. I would just name this function
uncheckFitToPageCheckbox().

Alternatively (i think this is better than previous suggestion) I would name it
onPrintScalingDisabled(). 

[kmadhusu, 2012/04/20 23:03:42]

+1 for onPrintScalingDisabled().

+      this.fitToPageCheckbox_.checked = false;
+    },
+
+    /**
+     * Adding listeners to fit to page control.
+     * @private
+     */
+    addEventListeners_: function() {
+      this.fitToPageCheckbox_.onclick =
+          this.onFitToPageCheckboxClicked_.bind(this);
+      document.addEventListener(customEvents.PDF_LOADED,
+                                this.onPDFLoaded_.bind(this));
+      document.addEventListener(customEvents.PRINTER_SELECTION_CHANGED,
+                                this.onPrinterSelectionChanged_.bind(this));
+    },
+
+    /**
+     * Listener executing when a |customEvents.PRINTER_SELECTION_CHANGED| event
+     * occurs.
+     * @param {cr.Event} event The event that triggered this listener.
+     * @private
+     */
+    onPrinterSelectionChanged_: function(event) {
+      this.resetState_(event.selectedPrinter);
+      this.updateVisibility_();
+    },
+
+    /**
+     * Listener executing when the user selects or de-selects the fit to page
+     * option.
+     * @private
+     */
+    onFitToPageCheckboxClicked_: function() {
+      requestPrintPreview();
+    },
+
+    /**
+     * Listener executing when a |customEvents.PDF_LOADED| event occurs.
+     * @private
+     */
+    onPDFLoaded_: function() {
+      this.updateVisibility_();
+    },
+
+    /**
+     * Hides or shows |this.fitToPageOption_|.
+     * @private
+     */
+    updateVisibility_: function() {
+      this.fitToPageOption_.style.display = this.fitToPageApplies_ ? 'block' :
+                                                                     'none';

[dpapad, 2012/04/19 21:11:29]

Nit: I believe it is more readable as follows.

this.fitToPageOption_.style.display =
    this.fitToPageApplies_ ? 'block' : 'none';        

[kmadhusu, 2012/04/20 23:03:42]

Done.

+    }
+  };
+
+  return {
+    FitToPageSettings: FitToPageSettings
+  };
+});