[CUPS] Implement the Webui handler for the printers auto discovery.

chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js

Index: chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
diff --git a/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js b/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
index e27685ae8d6bdcefa78c01d3cc26d098e3a592ee..ba7cd363c1b22d54a521bbe59e943b8dbb4b25dc 100644
--- a/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
+++ b/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js
@@ -26,11 +26,19 @@ var AddPrinterDialogs = {
   MANUFACTURER: 'add-printer-manufacturer-model-dialog',
 };
 
+/**
+ * The maximum height of the discovered printers list when the searching spinner
+ * is not showing.

[michaelpg, 2016/10/04 22:31:10]

@const {number}

[xdai1, 2016/10/04 23:36:19]

Done.

+ */
+var printerListFullHeight = 350;

[michaelpg, 2016/10/04 22:31:10]

kPrinterListFullHeight or PRINTER_LIST_FULL_HEIGHT

[xdai1, 2016/10/04 23:36:19]

Done.

+
 Polymer({
   is: 'add-printer-discovery-dialog',
 
+  behaviors: [WebUIListenerBehavior],
+
   properties: {
-    /** @type {!Array<!CupsPrinterInfo>} */
+    /** @type {!Array<!CupsPrinterInfo>|undefined} */
     discoveredPrinters: {
       type: Array,
     },
@@ -40,26 +48,71 @@ Polymer({
       type: Object,
       notify: true,
     },
+
+    discovering_: {
+      type: Boolean,
+      value: false,
+    },
   },
 
   /** @override */
   ready: function() {
-    // TODO(xdai): Get the discovered printer list after the API is ready.
+    this.discovering_ = true;

[michaelpg, 2016/10/04 22:31:10]

Why not set the initial value to true, above?

[xdai1, 2016/10/04 23:36:19]

Done.

+    settings.CupsPrintersBrowserProxyImpl.getInstance().
+        startDiscoveringPrinters();
+    this.addWebUIListener('on-printer-discovered',
+                          this.onPrinterDiscovered_.bind(this));
+    this.addWebUIListener('on-printer-discovery-done',
+                          this.onPrinterDiscoveryDone_.bind(this));
+    this.addWebUIListener('on-printer-discovery-failed',
+                          this.onPrinterDiscoveryDone_.bind(this));
+  },
+
+  /**
+   * @param {!Array<!CupsPrinterInfo>} printers
+   * @private
+   */
+  onPrinterDiscovered_: function(printers) {
+    this.discovering_ = true;
+    if (!this.discoveredPrinters)
+      this.discoveredPrinters = printers;
+    else
+      this.discoveredPrinters = this.discoveredPrinters.concat(printers);

[michaelpg, 2016/10/04 22:31:10]

instead of replacing the whole array (which might cause unnecessary work in
Polymer re-creating mostly the same DOM nodes), use this.push():

this.push.bind(this, 'discoveredPrinters').apply(printers);

see https://www.polymer-project.org/1.0/docs/api/Polymer.Base#method-push

[xdai1, 2016/10/04 23:36:19]

Seems like it could not push back a CupsPrinterInfo array directly to another
array. Thus push one by one.

+  },
+
+  /** @private */
+  onPrinterDiscoveryDone_: function() {
+    this.discovering_ = false;
+    this.$$('add-printer-list').style.maxHeight = printerListFullHeight + 'px';
+    if (!this.discoveredPrinters)
+      this.$.noPrinterMessage.hidden = false;

[michaelpg, 2016/10/04 22:31:10]

this.$.nPM.hidden = !!this.discoveredPrinters;

[xdai1, 2016/10/04 23:36:19]

Done.

+    else
+      this.$.noPrinterMessage.hidden = true;
+  },
+
+  /** @private */
+  stopDiscoveringPrinters_: function() {
+    settings.CupsPrintersBrowserProxyImpl.getInstance().
+        stopDiscoveringPrinters();
+    this.discovering_ = false;
   },
 
   /** @private */
   switchToManualAddDialog_: function() {
+    this.stopDiscoveringPrinters_();
     this.$$('add-printer-dialog').close();
     this.fire('open-manually-add-printer-dialog');
   },
 
   /** @private */
   onCancelTap_: function() {
+    this.stopDiscoveringPrinters_();
     this.$$('add-printer-dialog').close();
   },
 
   /** @private */
   switchToConfiguringDialog_: function() {
+    this.stopDiscoveringPrinters_();
     this.$$('add-printer-dialog').close();
     this.fire('open-configuring-printer-dialog');
   },
@@ -329,8 +382,14 @@ Polymer({
   openConfiguringPrinterDialog_: function() {
     this.switchDialog_(this.currentDialog_, AddPrinterDialogs.CONFIGURING,
                        'showConfiguringDialog_');
-    settings.CupsPrintersBrowserProxyImpl.getInstance().
-        addCupsPrinter(this.newPrinter);
+    if (this.previousDialog_ == AddPrinterDialogs.DISCOVERY) {
+      settings.CupsPrintersBrowserProxyImpl.getInstance().
+          addCupsPrinter(this.selectedPrinter);
+    } else if (this.previousDialog_ == AddPrinterDialogs.MANUALLY ||
+               this.previousDialog_ == AddPrinterDialogs.MANUFACTURER) {
+      settings.CupsPrintersBrowserProxyImpl.getInstance().
+          addCupsPrinter(this.newPrinter);
+    }
   },
 
   /** @private */
@@ -398,9 +457,11 @@ Polymer({
     if (success)
       return;
 
-    if (this.previousDialog_ == AddPrinterDialogs.MANUFACTURER)
+    if (this.previousDialog_ == AddPrinterDialogs.MANUFACTURER) {
       this.setupFailed = true;
-    this.switchDialog_(this.currentDialog_, AddPrinterDialogs.MANUFACTURER,
-                       'showManufacturerDialog_');
+    } else if (this.previousDialog_ == AddPrinterDialogs.MANUALLY) {
+      this.switchDialog_(this.currentDialog_, AddPrinterDialogs.MANUFACTURER,
+                         'showManufacturerDialog_');
+    }
   },
 });