Print Preview: Show an error when there are no printers

In kiosk app mode with no printers configured the preview spins forever
because in kiosk mode we cannot fall back to Save as PDF. This
currently only occurs on Chrome OS, as other platforms do not have app
kiosk mode. Handle this case gracefully by notifying the user that
there are no printers available.

Also update the change button to the old behavior of disabled during
load, since there should now be no case where the preview and
destinations settings show spinners indefinitely.

See the linked bug comment 9 for screenshot.

Bug: 903680
Change-Id: I2c3e9a5b41520176cd8fe170886d97e317df05d3
Reviewed-on: https://chromium-review.googlesource.com/c/1344836
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611528}

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

@@ -1170,6 +1170,7 @@ cr.define('print_preview', function() {
           this, DestinationStore.EventType.DESTINATION_SEARCH_DONE);
       if (type === print_preview.PrinterType.EXTENSION_PRINTER)
         this.endExtensionPrinterSearch_();
+      this.sendNoPrinterEventIfNeeded_();
     }
 
     /**
@@ -1270,6 +1271,23 @@ cr.define('print_preview', function() {
       }
       cr.dispatchSimpleEvent(
           this, DestinationStore.EventType.DESTINATION_SEARCH_DONE);
+      this.sendNoPrinterEventIfNeeded_();
+    }
+
+    /**
+     * Checks if the search is done and no printers are found. If so, fires a
+     * DestinationStore.EventType.NO_DESTINATIONS_FOUND event.
+     * @private
+     */
+    sendNoPrinterEventIfNeeded_() {
+      if (this.isPrintDestinationSearchInProgress ||
+          !this.selectFirstDestination_) {
+        return;
+      }
+
+      this.selectFirstDestination_ = false;
+      cr.dispatchSimpleEvent(
+          this, DestinationStore.EventType.NO_DESTINATIONS_FOUND);
     }
 
     /**
@@ -1397,6 +1415,8 @@ cr.define('print_preview', function() {
         'print_preview.DestinationStore.PROVISIONAL_DESTINATION_RESOLVED',
     CACHED_SELECTED_DESTINATION_INFO_READY:
         'print_preview.DestinationStore.CACHED_SELECTED_DESTINATION_INFO_READY',
+    NO_DESTINATIONS_FOUND:
+        'print_preview.DestinationStore.NO_DESTINATIONS_FOUND',
     SELECTED_DESTINATION_CAPABILITIES_READY: 'print_preview.DestinationStore' +
         '.SELECTED_DESTINATION_CAPABILITIES_READY',
     SELECTED_DESTINATION_INVALID:

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

@@ -194,6 +194,12 @@ Polymer({
         this.destinationStore_,
         print_preview.DestinationStore.EventType.DESTINATION_SELECT,
         this.onDestinationSelect_.bind(this));
+    // <if expr="chromeos">
+    this.tracker_.add(
+        this.destinationStore_,
+        print_preview.DestinationStore.EventType.NO_DESTINATIONS_FOUND,
+        this.onNoDestinationsFound_.bind(this));
+    // </if>
     this.tracker_.add(
         this.destinationStore_,
         print_preview.DestinationStore.EventType
@@ -656,6 +662,15 @@ Polymer({
     return this.settingsExpandedByUser_ || !this.shouldShowMoreSettings_;
   },
 
+  // <if expr="chromeos">
+  /** @private */
+  onNoDestinationsFound_: function() {
+    this.$.state.transitTo(print_preview_new.State.INVALID_PRINTER);
+    this.$.previewArea.setNoDestinationsFound();
+    this.$.destinationSettings.noDestinationsFound = true;
+  },
+  // </if>
+
   /** @private */
   close_: function() {
     this.$.state.transitTo(print_preview_new.State.CLOSING);

chrome/browser/resources/print_preview/new/destination_settings.html

@@ -2,6 +2,7 @@
 
 <link rel="import" href="chrome://resources/cr_elements/cr_lazy_render/cr_lazy_render.html">
 <link rel="import" href="chrome://resources/cr_elements/hidden_style_css.html">
+<link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/cr_elements/paper_button_style_css.html">
 <link rel="import" href="chrome://resources/cr_elements/shared_vars_css.html">
 <link rel="import" href="chrome://resources/html/event_tracker.html">
@@ -34,13 +35,15 @@
       }
 
       .destination-settings-box,
+      .no-destinations-display,
       .throbber-container {
         align-items: center;
         display: flex;
         overflow: hidden;
       }
 
-      .destination-settings-box iron-icon {
+      .destination-settings-box iron-icon,
+      .no-destinations-display iron-icon {
         fill: var(--google-grey-600);
         flex: 0;
         margin-inline-end: 8px;
@@ -63,7 +66,8 @@
       }
 
       .destination-info-wrapper > div,
-      .destination-throbber-name {
+      .destination-throbber-name,
+      .no-destinations-message {
         flex: 1;
         overflow: hidden;
         text-overflow: ellipsis;
@@ -77,10 +81,18 @@
     <print-preview-settings-section>
       <span slot="title">$i18n{destinationLabel}</span>
       <div slot="controls">
-        <div class="throbber-container" hidden="[[!loadingDestination_]]">
+        <div class="throbber-container"
+            hidden="[[!shouldShowSpinner_(
+                loadingDestination_, noDestinationsFound)]]">
           <div class="throbber"></div>
           <div class="destination-throbber-name"></div>
         </div>
+        <div class="no-destinations-display" hidden="[[!noDestinationsFound]]">
+          <iron-icon icon="cr:error"></iron-icon>
+          <div class="no-destinations-message">
+            $i18n{noDestinationsMessage}
+          </div>
+        </div>
         <div class="destination-settings-box" hidden="[[loadingDestination_]]">
           <iron-icon icon$="[[destination.icon]]" hidden="[[!destination]]">
           </iron-icon>
@@ -100,7 +112,7 @@
       <div slot="controls">
         <paper-button
           disabled$="[[shouldDisableButton_(destinationStore, disabled,
-                                            state)]]"
+                                            state, noDestinationsFound)]]"
           on-click="onChangeButtonClick_">
           $i18n{changeDestination}
         </paper-button>

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

@@ -31,6 +31,11 @@ Polymer({
     /** @type {!print_preview_new.State} */
     state: Number,
 
+    noDestinationsFound: {
+      type: Boolean,
+      value: false,
+    },
+
     /** @private {boolean} */
     showCloudPrintPromo_: {
       type: Boolean,
@@ -58,8 +63,8 @@ Polymer({
    * @private
    */
   shouldDisableButton_: function() {
-    return !this.destinationStore ||
-        (this.disabled && this.state != print_preview_new.State.NOT_READY &&
+    return !this.destinationStore || this.noDestinationsFound ||
+        (this.disabled &&
          this.state != print_preview_new.State.INVALID_PRINTER);
   },
 
@@ -68,6 +73,14 @@ Polymer({
     this.loadingDestination_ = !this.destination || !this.destination.id;
   },
 
+  /**
+   * @return {boolean} Whether to show the spinner.
+   * @private
+   */
+  shouldShowSpinner_: function() {
+    return this.loadingDestination_ && !this.noDestinationsFound;
+  },
+
   /**
    * @return {string} The connection status text to display.
    * @private

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

@@ -22,6 +22,9 @@ print_preview_new.PreviewAreaState = {
   INVALID_SETTINGS: 'invalid-settings',
   PREVIEW_FAILED: 'preview-failed',
   UNSUPPORTED_CLOUD_PRINTER: 'unsupported-cloud-printer',
+  // <if expr="chromeos">
+  NO_DESTINATIONS_FOUND: 'no-destinations-found',
+  // </if>
 };
 
 Polymer({
@@ -260,15 +263,15 @@ Polymer({
   currentMessage_: function() {
     switch (this.previewState) {
       case print_preview_new.PreviewAreaState.NO_PLUGIN:
-        return this.i18nAdvanced('noPlugin');
+        return this.i18n('noPlugin');
       case print_preview_new.PreviewAreaState.LOADING:
-        return this.i18nAdvanced('loading');
+        return this.i18n('loading');
       case print_preview_new.PreviewAreaState.DISPLAY_PREVIEW:
         return '';
       // <if expr="is_macosx">
       case print_preview_new.PreviewAreaState.OPEN_IN_PREVIEW_LOADING:
       case print_preview_new.PreviewAreaState.OPEN_IN_PREVIEW_LOADED:
-        return this.i18nAdvanced('openingPDFInPreview');
+        return this.i18n('openingPDFInPreview');
       // </if>
       case print_preview_new.PreviewAreaState.INVALID_SETTINGS:
         return this.i18nAdvanced('invalidPrinterSettings', {
@@ -276,12 +279,16 @@ Polymer({
           tags: ['BR'],
         });
       case print_preview_new.PreviewAreaState.PREVIEW_FAILED:
-        return this.i18nAdvanced('previewFailed');
+        return this.i18n('previewFailed');
       case print_preview_new.PreviewAreaState.UNSUPPORTED_CLOUD_PRINTER:
         return this.i18nAdvanced('unsupportedCloudPrinter', {
           substitutions: [],
           tags: ['BR'],
         });
+      // <if expr="chromeos">
+      case print_preview_new.PreviewAreaState.NO_DESTINATIONS_FOUND:
+        return this.i18n('noDestinationsMessage');
+      // </if>
       default:
         return '';
     }
@@ -317,6 +324,13 @@ Polymer({
     }
   },
 
+  // <if expr="chromeos">
+  setNoDestinationsFound: function() {
+    this.previewState =
+        print_preview_new.PreviewAreaState.NO_DESTINATIONS_FOUND;
+  },
+  // </if>
+
   // <if expr="is_macosx">
   /** Set the preview state to display the "opening in preview" message. */
   setOpeningPdfInPreview: function() {

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

@@ -12,6 +12,7 @@ cr.define('destination_select_test', function() {
     DefaultDestinationSelectionRules: 'default destination selection rules',
     SystemDefaultPrinterPolicy: 'system default printer policy',
     KioskModeSelectsFirstPrinter: 'kiosk mode selects first printer',
+    NoPrintersShowsError: 'no printers shows error',
   };
 
   const suiteName = 'DestinationSelectTests';
@@ -42,10 +43,13 @@ cr.define('destination_select_test', function() {
 
     /*
      * Sets the initial settings to the stored value and creates the page.
-     * @return {!Promise} Promise that resolves when initial settings and
-     *     printer capabilities have been returned.
+     * @param {boolean=} opt_expectPrinterFailure Whether printer fetch is
+     *     expected to fail
+     * @return {!Promise} Promise that resolves when initial settings and,
+     *     if printer failure is not expected, printer capabilities have
+     *     been returned.
      */
-    function setInitialSettings() {
+    function setInitialSettings(opt_expectPrinterFailure) {
       nativeLayer.setInitialSettings(initialSettings);
       nativeLayer.setLocalDestinations(localDestinations);
       print_preview.NativeLayer.setInstance(nativeLayer);
@@ -53,10 +57,10 @@ cr.define('destination_select_test', function() {
       page = document.createElement('print-preview-app');
       document.body.appendChild(page);
 
-      return Promise.all([
-        nativeLayer.whenCalled('getInitialSettings'),
-        nativeLayer.whenCalled('getPrinterCapabilities')
-      ]);
+      const promises = [nativeLayer.whenCalled('getInitialSettings')];
+      if (!opt_expectPrinterFailure)
+        promises.push(nativeLayer.whenCalled('getPrinterCapabilities'));
+      return Promise.all(promises);
     }
 
     /**
@@ -247,6 +251,38 @@ cr.define('destination_select_test', function() {
         assertPrinterDisplay(destinations[0].displayName);
       });
     });
+
+    /**
+     * Tests that if there is no system default destination, the default
+     * selection rules and recent destinations are empty, the preview
+     * is in app kiosk mode (so no PDF printer), and there are no
+     * destinations found, the no destinations found error is displayed.
+     */
+    test(assert(TestNames.NoPrintersShowsError), function() {
+      initialSettings.serializedDefaultDestinationSelectionRulesStr = '';
+      initialSettings.serializedAppStateStr = '';
+      initialSettings.isInAppKioskMode = true;
+      initialSettings.printerName = '';
+      localDestinations = [];
+
+      return Promise
+          .all([
+            setInitialSettings(true),
+            test_util.eventToPromise(
+                print_preview.DestinationStore.EventType.NO_DESTINATIONS_FOUND,
+                page.destinationStore_),
+          ])
+          .then(function() {
+            assertEquals(undefined, page.destination_);
+            const destinationSettings =
+                page.$$('print-preview-destination-settings');
+            assertTrue(destinationSettings.$$('.throbber-container').hidden);
+            assertTrue(
+                destinationSettings.$$('.destination-settings-box').hidden);
+            assertFalse(
+                destinationSettings.$$('.no-destinations-display').hidden);
+          });
+    });
   });
 
   return {

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

@@ -20,9 +20,10 @@ cr.define('destination_settings_test', function() {
       print_preview.NativeLayer.setInstance(nativeLayer);
       destinationSettings =
           document.createElement('print-preview-destination-settings');
-      destinationSettings.disabled = false;
       destinationSettings.destinationStore = null;
       destinationSettings.state = print_preview_new.State.NOT_READY;
+      // Disabled is true when state is NOT_READY.
+      destinationSettings.disabled = true;
       document.body.appendChild(destinationSettings);
     });
 
@@ -33,8 +34,8 @@ cr.define('destination_settings_test', function() {
       // Initial state: No destination store, button should be disabled.
       assertTrue(button.disabled);
 
-      // Set up the destination store, but no destination yet. Button is now
-      // enabled.
+      // Set up the destination store, but no destination yet. Button is
+      // disabled.
       const userInfo = new print_preview.UserInfo();
       const destinationStore = new print_preview.DestinationStore(
           userInfo, new WebUIListenerTracker());
@@ -44,7 +45,7 @@ cr.define('destination_settings_test', function() {
           [] /* recentDestinations */);
       destinationSettings.destinationStore = destinationStore;
       destinationSettings.state = print_preview_new.State.NOT_READY;
-      assertFalse(button.disabled);
+      assertTrue(button.disabled);
 
       // Simulate loading a destination and setting state to ready. The button
       // is still enabled.
@@ -53,6 +54,7 @@ cr.define('destination_settings_test', function() {
           print_preview.DestinationOrigin.LOCAL, 'FooName', true /* isRecent */,
           print_preview.DestinationConnectionStatus.ONLINE);
       destinationSettings.state = print_preview_new.State.READY;
+      destinationSettings.disabled = false;
       assertFalse(button.disabled);
 
       // Simulate setting a setting to an invalid value. Button is disabled due
@@ -68,6 +70,13 @@ cr.define('destination_settings_test', function() {
       destinationSettings.state = print_preview_new.State.INVALID_PRINTER;
       destinationSettings.disabled = true;
       assertFalse(button.disabled);
+
+      // Simulate the user having no printers.
+      destinationSettings.destination = null;
+      destinationSettings.state = print_preview_new.State.INVALID_PRINTER;
+      destinationSettings.disabled = true;
+      destinationSettings.noDestinationsFound = true;
+      assertTrue(button.disabled);
     });
   });
 

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

@@ -87,7 +87,8 @@ cr.define('print_preview', function() {
     /** @override */
     getPrinters(type) {
       this.methodCalled('getPrinters', type);
-      if (type == print_preview.PrinterType.LOCAL_PRINTER) {
+      if (type == print_preview.PrinterType.LOCAL_PRINTER &&
+          this.localDestinationInfos_.length > 0) {
         cr.webUIListenerCallback(
             'printers-added', type, this.localDestinationInfos_);
       } else if (

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

@@ -618,6 +618,7 @@ PrintPreviewDestinationSelectTest = class extends NewPrintPreviewTest {
   /** @override */
   get extraLibraries() {
     return super.extraLibraries.concat([
+      '../settings/test_util.js',
       '../test_browser_proxy.js',
       'native_layer_stub.js',
       'print_preview_test_utils.js',
@@ -675,6 +676,12 @@ TEST_F(
           destination_select_test.TestNames.KioskModeSelectsFirstPrinter);
     });
 
+GEN('#if defined(OS_CHROMEOS)');
+TEST_F('PrintPreviewDestinationSelectTest', 'NoPrintersShowsError', function() {
+  this.runMochaTest(destination_select_test.TestNames.NoPrintersShowsError);
+});
+GEN('#endif');
+
 PrintPreviewDestinationDialogTest = class extends NewPrintPreviewTest {
   /** @override */
   get browsePreload() {