Print Preview: Prefetch recent destinations

Prefetch capabilities for recent destinations. This will speed up
selection of these destinations and set up for adding a dropdown.

Bug: 920056
Change-Id: I2e53a8d353b91905dc1bec49f61815a4c416f052
Reviewed-on: https://chromium-review.googlesource.com/c/1404489
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622172}

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

@@ -396,13 +396,15 @@ cr.define('print_preview', function() {
       }
 
       this.recentDestinations_ = recentDestinations;
-      let origin = null;
-      let id = '';
-      let account = '';
-      let name = '';
-      let capabilities = null;
-      let extensionId = '';
-      let extensionName = '';
+      const destinationParams = {
+        origin: this.platformOrigin_,
+        id: '',
+        account: '',
+        name: '',
+        capabilities: null,
+        extensionId: '',
+        extensionName: '',
+      };
       let foundDestination = false;
       // Run through the destinations forward. As soon as we find a
       // destination, don't select any future destinations, just mark
@@ -410,25 +412,31 @@ cr.define('print_preview', function() {
       // destinations/updating the print ticket and this selecting a new
       // destination that causes random print preview errors.
       for (const destination of recentDestinations) {
-        origin = destination.origin;
-        id = destination.id;
-        account = destination.account || '';
-        name = destination.displayName || '';
-        capabilities = destination.capabilities;
-        extensionId = destination.extensionId || '';
-        extensionName = destination.extensionName || '';
-        const candidate =
-            this.destinationMap_[this.getDestinationKey_(origin, id, account)];
+        destinationParams.origin = assert(destination.origin);
+        destinationParams.id = destination.id;
+        destinationParams.account = destination.account || '';
+        destinationParams.name = destination.displayName || '';
+        destinationParams.capabilities = destination.capabilities;
+        destinationParams.extensionId = destination.extensionId || '';
+        destinationParams.extensionName = destination.extensionName || '';
+        const candidate = this.destinationMap_[this.getDestinationKey_(
+            destinationParams.origin, destinationParams.id,
+            destinationParams.account)];
         if (candidate != null) {
           candidate.isRecent = true;
           if (!foundDestination && !this.useSystemDefaultAsDefault_) {
             this.selectDestination(candidate);
           }
           foundDestination = true;
-        } else if (!foundDestination && !this.useSystemDefaultAsDefault_) {
-          foundDestination = this.fetchPreselectedDestination_(
-              origin, id, account, name, capabilities, extensionId,
-              extensionName);
+        } else {
+          // Only automatically select the destination if we are not using the
+          // system default and we have not already found a destination to
+          // select.
+          const autoSelect =
+              !foundDestination && !this.useSystemDefaultAsDefault_;
+          const foundNewDestination =
+              this.fetchPreselectedDestination_(destinationParams, autoSelect);
+          foundDestination = foundDestination || foundNewDestination;
         }
       }
 
@@ -437,21 +445,23 @@ cr.define('print_preview', function() {
       }
 
       // Try the system default
-      id = this.systemDefaultDestinationId_;
-      origin = id == print_preview.Destination.GooglePromotedId.SAVE_AS_PDF ?
+      destinationParams.id = this.systemDefaultDestinationId_;
+      destinationParams.origin = destinationParams.id ==
+              print_preview.Destination.GooglePromotedId.SAVE_AS_PDF ?
           print_preview.DestinationOrigin.LOCAL :
           this.platformOrigin_;
-      account = '';
+      destinationParams.account = '';
       const systemDefaultCandidate =
-          this.destinationMap_[this.getDestinationKey_(origin, id, account)];
+          this.destinationMap_[this.getDestinationKey_(
+              destinationParams.origin, destinationParams.id,
+              destinationParams.account)];
       if (systemDefaultCandidate != null) {
         this.selectDestination(systemDefaultCandidate);
         return;
       }
 
       if (this.fetchPreselectedDestination_(
-              origin, id, account, name, capabilities, extensionId,
-              extensionName)) {
+              destinationParams, true /* autoSelect */)) {
         return;
       }
 
@@ -459,25 +469,29 @@ cr.define('print_preview', function() {
     }
 
     /**
-     * Attempts to fetch capabilities of the destination identified by the
-     * provided origin, id and account.
-     * @param {print_preview.DestinationOrigin} origin Destination
-     *     origin.
-     * @param {string} id Destination id.
-     * @param {string} account User account destination is registered for.
-     * @param {string} name Destination display name.
-     * @param {?print_preview.Cdd} capabilities Destination capabilities.
-     * @param {string} extensionId Extension ID associated with this
-     *     destination.
-     * @param {string} extensionName Extension name associated with this
-     *     destination.
+     * Attempts to fetch capabilities of the destination identified by
+     * |destinationParams|.
+     * @param {!{
+     *   origin: !print_preview.DestinationOrigin,
+     *   id: string,
+     *   account: string,
+     *   name: string,
+     *   capabilities: ?print_preview.Cdd,
+     *   extensionId: string,
+     *   extensionName: string
+     * }} destinationParams Parameters identifying the destination.
+     * @param {boolean} autoSelect Whether to automatically select the
+     *     destination if it is fetched successfully.
      * @return {boolean} Whether capabilities fetch was successfully started.
      * @private
      */
-    fetchPreselectedDestination_(
-        origin, id, account, name, capabilities, extensionId, extensionName) {
-      this.autoSelectMatchingDestination_ =
-          this.createExactDestinationMatch_(origin, id);
+    fetchPreselectedDestination_(destinationParams, autoSelect) {
+      const id = destinationParams.id;
+      const origin = destinationParams.origin;
+      if (autoSelect) {
+        this.autoSelectMatchingDestination_ =
+            this.createExactDestinationMatch_(origin, id);
+      }
 
       const type = print_preview.originToType(origin);
       if (type == print_preview.PrinterType.LOCAL_PRINTER) {
@@ -490,7 +504,8 @@ cr.define('print_preview', function() {
       if (this.cloudPrintInterface_ &&
           (origin == print_preview.DestinationOrigin.COOKIES ||
            origin == print_preview.DestinationOrigin.DEVICE)) {
-        this.cloudPrintInterface_.printer(id, origin, account);
+        this.cloudPrintInterface_.printer(
+            id, origin, destinationParams.account);
         return true;
       }
 
@@ -500,23 +515,28 @@ cr.define('print_preview', function() {
         // privet or extension printers in this case.
         this.startLoadDestinations(type);
 
+        if (!autoSelect) {
+          return true;
+        }
+
         // Create a fake selectedDestination_ that is not actually in the
         // destination store. When the real destination is created, this
         // destination will be overwritten.
         const params =
             (origin === print_preview.DestinationOrigin.PRIVET) ? {} : {
               description: '',
-              extensionId: extensionId,
-              extensionName: extensionName,
+              extensionId: destinationParams.extensionId,
+              extensionName: destinationParams.extensionName,
               provisionalType: print_preview.DestinationProvisionalType.NONE
             };
         this.selectedDestination_ = new print_preview.Destination(
-            id, print_preview.DestinationType.LOCAL, origin, name,
-            false /*isRecent*/,
+            id, print_preview.DestinationType.LOCAL, origin,
+            destinationParams.name, false /*isRecent*/,
             print_preview.DestinationConnectionStatus.ONLINE, params);
 
-        if (capabilities) {
-          this.selectedDestination_.capabilities = capabilities;
+        if (destinationParams.capabilities) {
+          this.selectedDestination_.capabilities =
+              destinationParams.capabilities;
           this.dispatchEvent(
               new CustomEvent(DestinationStore.EventType
                                   .SELECTED_DESTINATION_CAPABILITIES_READY));
@@ -823,9 +843,16 @@ cr.define('print_preview', function() {
             !this.autoSelectMatchingDestination_.matchIdAndOrigin(
                 this.systemDefaultDestinationId_, this.platformOrigin_)) {
           if (this.fetchPreselectedDestination_(
-                  this.platformOrigin_, this.systemDefaultDestinationId_,
-                  '' /*account*/, '' /*name*/, null /*capabilities*/,
-                  '' /*extensionId*/, '' /*extensionName*/)) {
+                  {
+                    origin: this.platformOrigin_,
+                    id: this.systemDefaultDestinationId_,
+                    account: '',
+                    name: '',
+                    capabilities: null,
+                    extensionId: '',
+                    extensionName: ''
+                  },
+                  true /* autoSelect */)) {
             return;
           }
         }

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

@@ -32,6 +32,9 @@ cr.define('destination_select_test', function() {
     /** @type {!Array<!print_preview.Destination>} */
     let destinations = [];
 
+    /** @type {number} */
+    let numPrintersSelected = 0;
+
     /** @override */
     setup(function() {
       initialSettings = print_preview_test_utils.getDefaultInitialSettings();
@@ -57,11 +60,16 @@ cr.define('destination_select_test', function() {
       page = document.createElement('print-preview-app');
       document.body.appendChild(page);
 
-      const promises = [nativeLayer.whenCalled('getInitialSettings')];
-      if (!opt_expectPrinterFailure) {
-        promises.push(nativeLayer.whenCalled('getPrinterCapabilities'));
-      }
-      return Promise.all(promises);
+      return nativeLayer.whenCalled('getInitialSettings').then(() => {
+        page.destinationStore_.addEventListener(
+            print_preview.DestinationStore.EventType.DESTINATION_SELECT,
+            function() {
+              numPrintersSelected++;
+            });
+        return opt_expectPrinterFailure ?
+            Promise.resolve() :
+            nativeLayer.whenCalled('getPrinterCapabilities');
+      });
     }
 
     /**
@@ -93,9 +101,9 @@ cr.define('destination_select_test', function() {
         recentDestinations: [recentDestination],
       });
 
-      return setInitialSettings().then(function(argsArray) {
-        assertEquals('ID1', argsArray[1].destinationId);
-        assertEquals(print_preview.PrinterType.LOCAL, argsArray[1].type);
+      return setInitialSettings().then(function(args) {
+        assertEquals('ID1', args.destinationId);
+        assertEquals(print_preview.PrinterType.LOCAL, args.type);
         assertEquals('ID1', page.destination_.id);
         assertPrinterDisplay('One');
       });
@@ -116,11 +124,11 @@ cr.define('destination_select_test', function() {
       });
 
       return setInitialSettings()
-          .then(function(argsArray) {
+          .then(function(args) {
             // Should have loaded ID1 as the selected printer, since it was most
             // recent.
-            assertEquals('ID1', argsArray[1].destinationId);
-            assertEquals(print_preview.PrinterType.LOCAL, argsArray[1].type);
+            assertEquals('ID1', args.destinationId);
+            assertEquals(print_preview.PrinterType.LOCAL, args.type);
             assertEquals('ID1', page.destination_.id);
             assertPrinterDisplay('One');
 
@@ -158,11 +166,11 @@ cr.define('destination_select_test', function() {
       });
 
       return setInitialSettings()
-          .then(function(argsArray) {
+          .then(function(args) {
             // Should have loaded ID1 as the selected printer, since it was most
             // recent.
-            assertEquals('ID1', argsArray[1].destinationId);
-            assertEquals(print_preview.PrinterType.LOCAL, argsArray[1].type);
+            assertEquals('ID1', args.destinationId);
+            assertEquals(print_preview.PrinterType.LOCAL, args.type);
             assertEquals('ID1', page.destination_.id);
 
             return nativeLayer.whenCalled('getPreview');
@@ -172,18 +180,16 @@ cr.define('destination_select_test', function() {
             assertEquals(0, ticket.requestID);
             assertEquals('ID1', ticket.deviceName);
 
-            // None of the other printers should have been loaded. Should only
-            // have ID1 and Save as PDF. They will be loaded when the dialog is
-            // opened and startLoadDestinations() is called.
+            // The other recent destinations should be prefetched, but only one
+            // should have been selected so there was only one preview request.
             const reportedPrinters = page.destinationStore_.destinations();
-            assertEquals(2, reportedPrinters.length);
+            assertEquals(4, reportedPrinters.length);
             destinations.forEach((destination, index) => {
-              if (destination.id == 'ID1') {
-                return;
-              }
-
-              assertFalse(reportedPrinters.some(p => p.id == destination.id));
+              assertEquals(
+                  index < 3,
+                  reportedPrinters.some(p => p.id == destination.id));
             });
+            assertEquals(1, numPrintersSelected);
           });
     });
 
@@ -195,11 +201,11 @@ cr.define('destination_select_test', function() {
       initialSettings.serializedDefaultDestinationSelectionRulesStr =
           JSON.stringify({namePattern: '.*Four.*'});
       initialSettings.serializedAppStateStr = '';
-      return setInitialSettings().then(function(argsArray) {
+      return setInitialSettings().then(function(args) {
         // Should have loaded ID4 as the selected printer, since it matches
         // the rules.
-        assertEquals('ID4', argsArray[1].destinationId);
-        assertEquals(print_preview.PrinterType.LOCAL, argsArray[1].type);
+        assertEquals('ID4', args.destinationId);
+        assertEquals(print_preview.PrinterType.LOCAL, args.type);
         assertEquals('ID4', page.destination_.id);
         assertPrinterDisplay('Four');
       });
@@ -223,14 +229,20 @@ cr.define('destination_select_test', function() {
         recentDestinations: recentDestinations,
       });
 
-      return setInitialSettings().then(function(argsArray) {
-        // Need to load FooDevice as the printer, since it is the system
-        // default.
-        assertEquals('FooDevice', argsArray[1].destinationId);
-        assertEquals(print_preview.PrinterType.LOCAL, argsArray[1].type);
-        assertEquals('FooDevice', page.destination_.id);
-        assertPrinterDisplay('FooName');
-      });
+      return Promise
+          .all([
+            setInitialSettings(),
+            test_util.eventToPromise(
+                print_preview.DestinationStore.EventType
+                    .SELECTED_DESTINATION_CAPABILITIES_READY,
+                page.destinationStore_),
+          ])
+          .then(function(argsArray) {
+            // Need to load FooDevice as the printer, since it is the system
+            // default.
+            assertEquals('FooDevice', page.destination_.id);
+            assertPrinterDisplay('FooName');
+          });
     });
 
     /**
@@ -245,10 +257,10 @@ cr.define('destination_select_test', function() {
       initialSettings.isInAppKioskMode = true;
       initialSettings.printerName = '';
 
-      return setInitialSettings().then(function(argsArray) {
+      return setInitialSettings().then(function(args) {
         // Should have loaded the first destination as the selected printer.
-        assertEquals(destinations[0].id, argsArray[1].destinationId);
-        assertEquals(print_preview.PrinterType.LOCAL, argsArray[1].type);
+        assertEquals(destinations[0].id, args.destinationId);
+        assertEquals(print_preview.PrinterType.LOCAL, args.type);
         assertEquals(destinations[0].id, page.destination_.id);
         assertPrinterDisplay(destinations[0].displayName);
       });