Print Preview: Fix duplex defaults

Check the internals of the duplex capability, instead of only checking
for its existence, to determine whether to display the duplex checkbox.
Pull default value from the printer if it is available.

Currently a speculative fix, as have not been able to identify a
printer which sets the duplex capability field but does not actually
support duplex.

Bug: 896244
Change-Id: Iebafc3878a1e7658b821465439ee172c479ce413
Reviewed-on: https://chromium-review.googlesource.com/c/1290145
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601790}

chrome/browser/resources/print_preview/new/model.js

@@ -55,6 +55,16 @@ print_preview_new.DuplexMode = {
   UNKNOWN_DUPLEX_MODE: -1
 };
 
+/**
+ * Values matching the types of duplex in a CDD.
+ * @enum {string}
+ */
+print_preview_new.DuplexType = {
+  NO_DUPLEX: 'NO_DUPLEX',
+  LONG_EDGE: 'LONG_EDGE',
+  SHORT_EDGE: 'SHORT_EDGE'
+};
+
 (function() {
 'use strict';
 
@@ -380,7 +390,15 @@ Polymer({
         'settings.dpi.available',
         !!caps && !!caps.dpi && !!caps.dpi.option &&
             caps.dpi.option.length > 1);
-    this.set('settings.duplex.available', !!caps && !!caps.duplex);
+
+    this.set(
+        'settings.duplex.available',
+        !!caps && !!caps.duplex && !!caps.duplex.option &&
+            caps.duplex.option.some(
+                o => o.type == print_preview_new.DuplexType.LONG_EDGE) &&
+            caps.duplex.option.some(
+                o => o.type == print_preview_new.DuplexType.NO_DUPLEX));
+
     this.set(
         'settings.vendorItems.available', !!caps && !!caps.vendor_capability);
 
@@ -546,6 +564,24 @@ Polymer({
       this.set('settings.color.unavailableValue', false);
     }
 
+    if (this.settings.duplex.available) {
+      const defaultOption = caps.duplex.option.find(o => !!o.is_default);
+      this.setSetting(
+          'duplex',
+          defaultOption ?
+              defaultOption.type == print_preview_new.DuplexType.LONG_EDGE :
+              false);
+    } else if (
+        caps && caps.duplex && caps.duplex.option &&
+        !caps.duplex.option.some(
+            o => o.type != print_preview_new.DuplexType.LONG_EDGE)) {
+      // If the only option available is long edge, the value should always be
+      // true.
+      this.set('settings.duplex.unavailableValue', true);
+    } else {  // If no duplex capability is reported, assume false.
+      this.set('settings.duplex.unavailableValue', false);
+    }
+
     if (this.settings.vendorItems.available) {
       const vendorSettings = {};
       for (const item of caps.vendor_capability) {
@@ -818,7 +854,9 @@ Polymer({
       cjt.print.copies = {copies: parseInt(this.getSettingValue('copies'), 10)};
     if (this.settings.duplex.available) {
       cjt.print.duplex = {
-        type: this.settings.duplex.value ? 'LONG_EDGE' : 'NO_DUPLEX'
+        type: this.settings.duplex.value ?
+            print_preview_new.DuplexType.LONG_EDGE :
+            print_preview_new.DuplexType.NO_DUPLEX,
       };
     }
     if (this.settings.mediaSize.available) {

chrome/test/data/webui/print_preview/settings_section_test.js

@@ -430,6 +430,19 @@ cr.define('settings_sections_tests', function() {
       assertFalse(optionsElement.hidden);
       assertTrue(isSectionHidden(duplex));
 
+      // Set a duplex capability with only 1 type, no duplex.
+      capabilities =
+          print_preview_test_utils.getCddTemplate('FooPrinter').capabilities;
+      delete capabilities.printer.duplex;
+      capabilities.printer.duplex = {
+        option:
+            [{type: print_preview_new.DuplexType.NO_DUPLEX, is_default: true}]
+      };
+      page.set('destination_.capabilities', capabilities);
+      Polymer.dom.flush();
+      assertFalse(optionsElement.hidden);
+      assertTrue(isSectionHidden(duplex));
+
       // PDF
       initDocumentInfo(true, false);
       Polymer.dom.flush();
@@ -1023,7 +1036,9 @@ cr.define('settings_sections_tests', function() {
 
       return testOptionCheckbox('headerFooter', true)
           .then(function() {
-            return testOptionCheckbox('duplex', true);
+            // Duplex defaults to false, since the printer sets no duplex as the
+            // default in the CDD (see print_preview_test_utils.js).
+            return testOptionCheckbox('duplex', false);
           })
           .then(function() {
             return testOptionCheckbox('cssBackground', false);