Print Preview: Fixing behavior of event listeners.

chrome/browser/resources/print_preview/print_preview.js

Index: chrome/browser/resources/print_preview/print_preview.js
diff --git a/chrome/browser/resources/print_preview/print_preview.js b/chrome/browser/resources/print_preview/print_preview.js
index 35ec000338f2f92da3c38462ea19c040f2c210a9..f6b6f5301ba2d3d8eef781927164013f5b0eadc2 100644
--- a/chrome/browser/resources/print_preview/print_preview.js
+++ b/chrome/browser/resources/print_preview/print_preview.js
@@ -36,6 +36,9 @@ var hasPendingPreviewRequest = false;
 // The ID of the last preview request.
 var lastPreviewRequestID = -1;
 
+// The ID of the initial preview request.
+var initialPreviewRequestID = -1;
+
 // True when a pending print file request exists.
 var hasPendingPrintDocumentRequest = false;
 
@@ -74,12 +77,18 @@ var addedCloudPrinters = {};
 // The maximum number of cloud printers to allow in the dropdown.
 const maxCloudPrinters = 10;
 
+const MIN_REQUEST_ID = 0;
+const MAX_REQUEST_ID = 32000;
+
 /**
  * Window onload handler, sets up the page and starts print preview by getting
  * the printer list.
  */
 function onLoad() {
   cr.enablePlatformSpecificCSSRules();
+  initialPreviewRequestID = getRandomIntegerWithinRange(MIN_REQUEST_ID,
+                                                        MAX_REQUEST_ID);
+  lastPreviewRequestID = initialPreviewRequestID;
 
   if (!checkCompatiblePluginExists()) {
     disableInputElementsInSidebar();
@@ -105,31 +114,13 @@ function onLoad() {
   copiesSettings.addEventListeners();
   layoutSettings.addEventListeners();
   colorSettings.addEventListeners();
+  $('printer-list').onchange = updateControlsWithSelectedPrinterCapabilities;
 
   showLoadingAnimation();
   chrome.send('getDefaultPrinter');
 }
 
 /**
- * Adds event listeners to the settings controls.
- */
-function addEventListeners() {
-  // Controls that require preview rendering.
-  $('printer-list').onchange = updateControlsWithSelectedPrinterCapabilities;
-}
-
-/**
- * Removes event listeners from the settings controls.
- */
-function removeEventListeners() {
-  if (pageSettings)
-    clearTimeout(pageSettings.timerId_);
-
-  // Controls that require preview rendering
-  $('printer-list').onchange = null;
-}
-
-/**
  * Disables the input elements in the sidebar.
  */
 function disableInputElementsInSidebar() {
@@ -311,6 +302,7 @@ function getSettings() {
        'landscape': layoutSettings.isLandscape(),
        'color': colorSettings.isColor(),
        'printToPDF': printToPDF,
+       'isFirstRequest' : false,
        'requestID': 0};
 
   var printerList = $('printer-list');
@@ -333,7 +325,15 @@ function generatePreviewRequestID() {
  * @return {boolean} True iff a preview has been requested.
  */
 function hasRequestedPreview() {
-  return lastPreviewRequestID > -1;
+  return lastPreviewRequestID != initialPreviewRequestID;
+}
+
+/**
+ * @return {boolean} True if |lastPreviewRequestID| corresponds to the initial
+ *     preview request.
+ */
+function isFirstPreviewRequest() {
+  return lastPreviewRequestID == initialPreviewRequestID + 1;
 }
 
 /**
@@ -381,7 +381,6 @@ function requestToPrintDocument() {
   if (printToPDF) {
     sendPrintDocumentRequest();
   } else {
-    removeEventListeners();
     window.setTimeout(function() { sendPrintDocumentRequest(); }, 1000);
   }
 }
@@ -425,13 +424,13 @@ function sendPrintDocumentRequest() {
  */
 function requestPrintPreview() {
   hasPendingPreviewRequest = true;
-  removeEventListeners();
   printSettings.save();
   if (!isTabHidden)
     showLoadingAnimation();
 
   var settings = getSettings();
   settings.requestID = generatePreviewRequestID();
+  settings.isFirstRequest = isFirstPreviewRequest();
   chrome.send('getPreview', [JSON.stringify(settings)]);
 }
 
@@ -731,7 +730,6 @@ function displayErrorMessage(errorMessage) {
   $('dancing-dots-text').classList.add('hidden');
   $('error-text').innerHTML = errorMessage;
   $('error-text').classList.remove('hidden');
-  removeEventListeners();
   var pdfViewer = $('pdf-viewer');
   if (pdfViewer)
     $('mainview').removeChild(pdfViewer);
@@ -774,7 +772,6 @@ function printPreviewFailed() {
 function onPDFLoad() {
   if (previewModifiable) {
     setPluginPreviewPageCount();
-    cr.dispatchSimpleEvent(document, 'updateSummary');
   }
   $('pdf-viewer').fitToHeight();
   cr.dispatchSimpleEvent(document, 'PDFLoaded');
@@ -792,14 +789,22 @@ function setPluginPreviewPageCount() {
  * @param {number} pageCount The number of pages.
  * @param {boolean} isModifiable Indicates whether the previewed document can be
  *     modified.
+ * @param {number} previewResponseId The preview request id that resulted in
+ *     this response.
  */
-function onDidGetPreviewPageCount(pageCount, isModifiable) {
+function onDidGetPreviewPageCount(pageCount, isModifiable, previewResponseId) {
+  if (!isExpectedPreviewResponse(previewResponseId))
+    return;
   pageSettings.updateState(pageCount);
   previewModifiable = isModifiable;
+  cr.dispatchSimpleEvent(document, 'updateSummary');
 }
 
 /**
  * Called when no pipelining previewed pages.
+ * @param {string} previewUid Preview unique identifier.
+ * @param {number} previewResponseId The preview request id that resulted in
+ *     this response.
  */
 function reloadPreviewPages(previewUid, previewResponseId) {
   if (!isExpectedPreviewResponse(previewResponseId))
@@ -808,9 +813,7 @@ function reloadPreviewPages(previewUid, previewResponseId) {
 
   if (checkIfSettingsChangedAndRegeneratePreview())
     return;
-  cr.dispatchSimpleEvent(document, 'updateSummary');
   cr.dispatchSimpleEvent(document, 'updatePrintButton');
-  addEventListeners();
   hideLoadingAnimation();
   var pageSet = pageSettings.previouslySelectedPages;
   for (var i = 0; i < pageSet.length; i++)
@@ -823,8 +826,14 @@ function reloadPreviewPages(previewUid, previewResponseId) {
  * Check if the settings have changed and request a regeneration if needed.
  * Called from PrintPreviewUI::OnDidPreviewPage().
  * @param {number} pageNumber The page number, 0-based.
+ * @param {string} previewUid Preview unique identifier.
+ * @param {number} previewResponseId The preview request id that resulted in
+ *     this response.
  */
-function onDidPreviewPage(pageNumber, previewUid) {
+function onDidPreviewPage(pageNumber, previewUid, previewResponseId) {
+  if (!isExpectedPreviewResponse(previewResponseId))
+    return;
+
   // Refactor
   if (!previewModifiable)
     return;
@@ -867,9 +876,7 @@ function updatePrintPreview(jobTitle,
     createPDFPlugin(previewUid);
   }
 
-  cr.dispatchSimpleEvent(document, 'updateSummary');
   cr.dispatchSimpleEvent(document, 'updatePrintButton');
-  addEventListeners();
 
   if (hasPendingPrintDocumentRequest)
     requestToPrintPendingDocument();