Perform printer setup on Chrome OS before selecting printer.

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

Index: chrome/browser/resources/print_preview/data/destination_store.js
diff --git a/chrome/browser/resources/print_preview/data/destination_store.js b/chrome/browser/resources/print_preview/data/destination_store.js
index dafd6553b237f3a68c0e279e159bd63c44167ed7..04bc44fdb5188179b7252705df1cdebd9f9f95d7 100644
--- a/chrome/browser/resources/print_preview/data/destination_store.js
+++ b/chrome/browser/resources/print_preview/data/destination_store.js
@@ -280,11 +280,30 @@ cr.define('print_preview', function() {
      */
     this.waitForRegisterDestination_ = null;
 
+    /**
+     * Local destinations are CROS destinations on ChromeOS because they require
+     * extra setup.
+     * @type {!print_preview.Destination.Origin}
+     * @private
+     */
+    this.platformOrigin_ = cr.isChromeOS ?
+        print_preview.Destination.Origin.CROS :
+        print_preview.Destination.Origin.LOCAL;
+
     this.addEventListeners_();
     this.reset_();
   };
 
   /**
+   * @typedef {{
+   *   printerId: string,
+   *   success: boolean,
+   *   capabilities: Object,
+   * }}
+   */
+  var PrinterSetupResponse;
+
+  /**
    * Event types dispatched by the data store.
    * @enum {string}
    */
@@ -301,7 +320,9 @@ cr.define('print_preview', function() {
     CACHED_SELECTED_DESTINATION_INFO_READY:
         'print_preview.DestinationStore.CACHED_SELECTED_DESTINATION_INFO_READY',
     SELECTED_DESTINATION_CAPABILITIES_READY:
-        'print_preview.DestinationStore.SELECTED_DESTINATION_CAPABILITIES_READY'
+        'print_preview.DestinationStore.SELECTED_DESTINATION_CAPABILITIES_READY',
+    PRINTER_CONFIGURED:
+        'print_preview.DestinationStore.PRINTER_CONFIGURED',
   };
 
   /**
@@ -690,8 +711,8 @@ cr.define('print_preview', function() {
         return;
       }
 
-      var origin = print_preview.Destination.Origin.LOCAL;
-      var id = this.systemDefaultDestinationId_;
+      var origin = null;
+      var id = '';
       var account = '';
       var name = '';
       var capabilities = null;
@@ -735,7 +756,13 @@ cr.define('print_preview', function() {
         }
       }
       if (foundDestination) return;
+
       // Try the system default
+      id = this.systemDefaultDestinationId_;
+      origin = id == print_preview.Destination.GooglePromotedId.SAVE_AS_PDF ?
+          print_preview.Destination.Origin.LOCAL :
+          this.platformOrigin_;
+      account = '';
       var candidate =
           this.destinationMap_[this.getDestinationKey_(origin, id, account)];
       if (candidate != null) {
@@ -776,7 +803,8 @@ cr.define('print_preview', function() {
       this.autoSelectMatchingDestination_ =
           this.createExactDestinationMatch_(origin, id);
 
-      if (origin == print_preview.Destination.Origin.LOCAL) {
+      if (origin == print_preview.Destination.Origin.LOCAL ||
+          origin == print_preview.Destination.Origin.CROS) {
         this.nativeLayer_.startGetLocalDestinationCapabilities(id);
         return true;
       }
@@ -847,7 +875,9 @@ cr.define('print_preview', function() {
       this.autoSelectMatchingDestination_ = destinationMatch;
 
       if (destinationMatch.matchOrigin(
-            print_preview.Destination.Origin.LOCAL)) {
+            print_preview.Destination.Origin.LOCAL) ||
+          destinationMatch.matchOrigin(
+            print_preview.Destination.Origin.CROS)) {
         this.startLoadLocalDestinations();
       }
       if (destinationMatch.matchOrigin(
@@ -902,6 +932,7 @@ cr.define('print_preview', function() {
         origins.push(print_preview.Destination.Origin.LOCAL);
         origins.push(print_preview.Destination.Origin.PRIVET);
         origins.push(print_preview.Destination.Origin.EXTENSION);
+        origins.push(print_preview.Destination.Origin.CROS);
       }
       if (isCloud) {
         origins.push(print_preview.Destination.Origin.COOKIES);
@@ -947,7 +978,7 @@ cr.define('print_preview', function() {
       }
       if (this.systemDefaultDestinationId_) {
         return this.createExactDestinationMatch_(
-            print_preview.Destination.Origin.LOCAL,
+            this.platformOrigin_,
             this.systemDefaultDestinationId_);
       }
       return null;
@@ -1084,6 +1115,18 @@ cr.define('print_preview', function() {
     },
 
     /**
+     * Attempt to resolve the capabilities for a Chrome OS printer.
+     * @param {!print_preview.Destination} destination The destination which
+     *     requires resolution.
+     */
+    resolveCrosDestination: function(destination) {
+      assert(destination.origin == print_preview.Destination.Origin.CROS);
+      this.nativeLayer_.setupPrinter(destination.id).

[dpapad, 2017/01/12 01:18:10]

There is no need to call both then and catch. then() accepts a 2nd parameter.
Also I think this would be simpler if you simply inline the two handling
functions here, as follows.

this.nativeLayer_.setupPrinter(destination.id).then(
  function(response) {
    var event = ...;
    ...
    this.dispatchEvent(event);
  }.bind(this),
  function() { // You don't even need the parameter anymore, just use
destination.id
    ...
  }.bind(this));

[skau, 2017/01/12 02:17:17]

Done.

+          then(this.onPrinterSetup_.bind(this)).
+          catch(this.onPrinterFailure_.bind(this));
+    },
+
+    /**
      * Attempts to resolve a provisional destination.
      * @param {!print_preview.Destination} destinaion Provisional destination
      *     that should be resolved.
@@ -1119,9 +1162,9 @@ cr.define('print_preview', function() {
         if (this.autoSelectMatchingDestination_ &&
             !this.autoSelectMatchingDestination_.matchIdAndOrigin(
                 this.systemDefaultDestinationId_,
-                print_preview.Destination.Origin.LOCAL)) {
+                this.plaformOrigin_)) {
           if (this.fetchPreselectedDestination_(
-                print_preview.Destination.Origin.LOCAL,
+                this.platformOrigin_,
                 this.systemDefaultDestinationId_,
                 '' /*account*/,
                 '' /*name*/,
@@ -1272,6 +1315,32 @@ cr.define('print_preview', function() {
     },
 
     /**
+     * Handle the result of a PRINTER_SETUP request.
+     * @param {!PrinterSetupResponse} response.
+     * @private
+     */
+    onPrinterSetup_: function(response) {
+      var event = new Event(

[dpapad, 2017/01/12 01:18:10]

Technically, we should not be augmenting a native Event with extra properties. A
much simpler (and robust) way is to use a class specifically made for custom
events, called CustomEvent
(https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent).

For example this could look as simple as follows

var event = new CustomEvent(
  DestinationStore.EventType.PRINTER_CONFIGURED,
  {detail: response});
this.dispatchEvent(event);

Then consumers of the event can simply refer to the "payload" of the event as
"event.detail".

I am not suggesting to do this now. We should probably cleanup all "new Event"
occurrences in print_preview/ at some point.

[skau, 2017/01/12 02:17:17]

It seems to lead to much cleaner code.  I'll use it for this.

+          DestinationStore.EventType.PRINTER_CONFIGURED);
+      event.printerId = response.printerId;
+      event.capabilities = response.capabilities;
+      event.success = response.success;
+      this.dispatchEvent(event);
+    },
+
+    /**
+     * Calling printer setup failed.
+     * @param {string} printerId The printer for which the request failed.
+     */
+    onPrinterFailure_: function(printerId) {
+      var event = new Event(
+          DestinationStore.EventType.PRINTER_CONFIGURED);
+      event.printerId = printerId;
+      event.success = false;
+      this.dispatchEvent(event);
+    },
+
+    /**
      * Inserts {@code destination} to the data store and dispatches a
      * DESTINATIONS_INSERTED event.
      * @param {!print_preview.Destination} destination Print destination to
@@ -1524,8 +1593,13 @@ cr.define('print_preview', function() {
       var destinationId = event.settingsInfo['printerId'];
       var printerName = event.settingsInfo['printerName'];
       var printerDescription = event.settingsInfo['printerDescription'];
+      // PDF is special since we don't need to query the device for
+      // capabilities.
+      var origin = destinationId ==
+          print_preview.Destination.GooglePromotedId.SAVE_AS_PDF ?
+          print_preview.Destination.Origin.LOCAL : this.platformOrigin_;
       var key = this.getDestinationKey_(
-          print_preview.Destination.Origin.LOCAL,
+          origin,
           destinationId,
           '');
       var destination = this.destinationMap_[key];