Print Preview: Change getPrinters to cr.sendWithPromise

Change one more native layer message to cr.sendWithPromise and adjust
tests to use browser proxy for this message instead of triggering an
event.

BUG=717296
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2919693002
Cr-Commit-Position: refs/heads/master@{#476503}

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

@@ -1078,7 +1078,8 @@ cr.define('print_preview', function() {
     startLoadLocalDestinations: function() {
       if (!this.hasLoadedAllLocalDestinations_) {
         this.hasLoadedAllLocalDestinations_ = true;
-        this.nativeLayer_.startGetLocalDestinations();
+        this.nativeLayer_.getPrinters().then(
+            this.onLocalDestinationsSet_.bind(this));
         this.isLocalDestinationSearchInProgress_ = true;
         cr.dispatchSimpleEvent(
             this, DestinationStore.EventType.DESTINATION_SEARCH_STARTED);
@@ -1360,10 +1361,6 @@ cr.define('print_preview', function() {
      */
     addEventListeners_: function() {
       var nativeLayerEventTarget = this.nativeLayer_.getEventTarget();
-      this.tracker_.add(
-          nativeLayerEventTarget,
-          print_preview.NativeLayer.EventType.LOCAL_DESTINATIONS_SET,
-          this.onLocalDestinationsSet_.bind(this));
       this.tracker_.add(
           nativeLayerEventTarget,
           print_preview.NativeLayer.EventType.CAPABILITIES_SET,
@@ -1437,11 +1434,12 @@ cr.define('print_preview', function() {
 
     /**
      * Called when the local destinations have been got from the native layer.
-     * @param {Event} event Contains the local destinations.
+     * @param {!Array<!print_preview.LocalDestinationInfo>} destinationInfos A
+     *     list of the local destinations retrieved.
      * @private
      */
-    onLocalDestinationsSet_: function(event) {
-      var localDestinations = event.destinationInfos.map(function(destInfo) {
+    onLocalDestinationsSet_: function(destinationInfos) {
+      var localDestinations = destinationInfos.map(function(destInfo) {
         return print_preview.LocalDestinationParser.parse(destInfo);
       });
       this.insertDestinations_(localDestinations);

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

@@ -10,8 +10,8 @@ cr.define('print_preview', function() {
 
   /**
    * Parses a local print destination.
-   * @param {!Object} destinationInfo Information describing a local print
-   *     destination.
+   * @param {!print_preview.LocalDestinationInfo} destinationInfo Information
+   *     describing a local print destination.
    * @return {!print_preview.Destination} Parsed local print destination.
    */
   LocalDestinationParser.parse = function(destinationInfo) {

chrome/browser/resources/print_preview/native_layer.js

@@ -15,6 +15,17 @@ cr.exportPath('print_preview');
  */
 print_preview.PreviewSettings;
 
+/**
+ * @typedef {{
+ *   deviceName: string,
+ *   printerName: string,
+ *   printerDescription: (string | undefined),
+ *   cupsEnterprisePrinter: (boolean | undefined),
+ *   printerOptions: (Object | undefined),
+ * }}
+ */
+print_preview.LocalDestinationInfo;
+
 /**
  * @typedef {{
  *   printerId: string,
@@ -34,7 +45,6 @@ cr.define('print_preview', function() {
   function NativeLayer() {
     // Bind global handlers
     global.setUseCloudPrint = this.onSetUseCloudPrint_.bind(this);
-    global.setPrinters = this.onSetPrinters_.bind(this);
     global.updateWithPrinterCapabilities =
         this.onUpdateWithPrinterCapabilities_.bind(this);
     global.failedToGetPrinterCapabilities =
@@ -220,9 +230,10 @@ cr.define('print_preview', function() {
     /**
      * Requests the system's local print destinations. A LOCAL_DESTINATIONS_SET
      * event will be dispatched in response.
+     * @return {!Promise<!Array<print_preview.LocalDestinationInfo>>}
      */
-    startGetLocalDestinations: function() {
-      chrome.send('getPrinters');
+    getPrinters: function() {
+      return cr.sendWithPromise('getPrinters');
     },
 
     /**
@@ -549,19 +560,6 @@ cr.define('print_preview', function() {
       this.eventTarget_.dispatchEvent(cloudPrintEnableEvent);
     },
 
-    /**
-     * Updates the print preview with local printers.
-     * Called from PrintPreviewHandler::SetupPrinterList().
-     * @param {Array} printers Array of printer info objects.
-     * @private
-     */
-    onSetPrinters_: function(printers) {
-      var localDestsSetEvent = new Event(
-          NativeLayer.EventType.LOCAL_DESTINATIONS_SET);
-      localDestsSetEvent.destinationInfos = printers;
-      this.eventTarget_.dispatchEvent(localDestsSetEvent);
-    },
-
     /**
      * Called when native layer gets settings information for a requested local
      * destination.

chrome/browser/ui/webui/print_preview/print_preview_handler.cc

@@ -661,10 +661,17 @@ printing::PrinterBackendProxy* PrintPreviewHandler::printer_backend_proxy() {
   return printer_backend_proxy_.get();
 }
 
-void PrintPreviewHandler::HandleGetPrinters(const base::ListValue* /*args*/) {
+void PrintPreviewHandler::HandleGetPrinters(const base::ListValue* args) {
   VLOG(1) << "Enumerate printers start";
-  printer_backend_proxy()->EnumeratePrinters(base::Bind(
-      &PrintPreviewHandler::SetupPrinterList, weak_factory_.GetWeakPtr()));
+  std::string callback_id;
+  CHECK(args->GetString(0, &callback_id));
+  CHECK(!callback_id.empty());
+
+  AllowJavascript();
+
+  printer_backend_proxy()->EnumeratePrinters(
+      base::Bind(&PrintPreviewHandler::SetupPrinterList,
+                 weak_factory_.GetWeakPtr(), callback_id));
 }
 
 void PrintPreviewHandler::HandleGetPrivetPrinters(const base::ListValue* args) {
@@ -1325,6 +1332,7 @@ void PrintPreviewHandler::SendPrinterSetup(
 }
 
 void PrintPreviewHandler::SetupPrinterList(
+    const std::string& callback_id,
     const printing::PrinterList& printer_list) {
   base::ListValue printers;
   PrintersToValues(printer_list, &printers);
@@ -1337,7 +1345,7 @@ void PrintPreviewHandler::SetupPrinterList(
     has_logged_printers_count_ = true;
   }
 
-  web_ui()->CallJavascriptFunctionUnsafe("setPrinters", printers);
+  ResolveJavascriptCallback(base::Value(callback_id), printers);
 }
 
 void PrintPreviewHandler::SendCloudPrintEnabled() {

chrome/browser/ui/webui/print_preview/print_preview_handler.h

@@ -242,7 +242,8 @@ class PrintPreviewHandler
                         std::unique_ptr<base::DictionaryValue> settings_info);
 
   // Send the list of printers to the Web UI.
-  void SetupPrinterList(const printing::PrinterList& printer_list);
+  void SetupPrinterList(const std::string& callback_id,
+                        const printing::PrinterList& printer_list);
 
   // Send whether cloud print integration should be enabled.
   void SendCloudPrintEnabled();

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

@@ -10,7 +10,7 @@ cr.define('print_preview', function() {
   */
   function NativeLayerStub() {
     settings.TestBrowserProxy.call(this, [
-        'getInitialSettings', 'setupPrinter' ]);
+        'getInitialSettings', 'getPrinters', 'setupPrinter' ]);
 
     /**
      * @private {!cr.EventTarget} The event target used for dispatching and
@@ -33,6 +33,13 @@ cr.define('print_preview', function() {
      */
     this.initialSettings_ = null;
 
+    /**
+     *
+     * @private {!Array<!print_preview.LocalDestinationInfo>} Local destination
+     *     list to be used for the response to |getPrinters|.
+     */
+    this.localDestinationInfos_ = [];
+
     /**
      * @private {!print_preview.PrinterSetupResponse} The response to be sent
      *     on a |setupPrinter| call.
@@ -66,6 +73,12 @@ cr.define('print_preview', function() {
       return Promise.resolve(this.initialSettings_);
     },
 
+    /** @override */
+    getPrinters: function() {
+      this.methodCalled('getPrinters');
+      return Promise.resolve(this.localDestinationInfos_);
+    },
+
     /** @override */
     setupPrinter: function(printerId) {
       this.methodCalled('setupPrinter', printerId);
@@ -131,6 +144,14 @@ cr.define('print_preview', function() {
       this.initialSettings_ = settings;
     },
 
+    /**
+     * @param {!Array<!print_preview.LocalDestinationInfo>} localDestinations
+     *     The local destinations to return as a response to |getPrinters|.
+     */
+    setLocalDestinations: function(localDestinations) {
+      this.localDestinationInfos_ = localDestinations;
+    },
+
     /**
      * @param {boolean} reject Whether printSetup requests should be rejected.
      * @param {!print_preview.PrinterSetupResponse} The response to send when