Process null capabilities as a capability fetch failure.

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 e26fd399352ff61a1b99898def8c13e985bd0cb1..2f577a5556799f658f843edb8710803b659d8c71 100644
--- a/chrome/browser/resources/print_preview/data/destination_store.js
+++ b/chrome/browser/resources/print_preview/data/destination_store.js
@@ -1543,6 +1543,9 @@ cr.define('print_preview', function() {
      * @private
      */
     onLocalDestinationCapabilitiesSet_: function(event) {
+      var rawCapabilities = event.settingsInfo.capabilities;
+      assert(rawCapabilities);
+
       var destinationId = event.settingsInfo['printerId'];
       var printerName = event.settingsInfo['printerName'];
       var printerDescription = event.settingsInfo['printerDescription'];
@@ -1557,7 +1560,7 @@ cr.define('print_preview', function() {
           '');
       var destination = this.destinationMap_[key];
       var capabilities = DestinationStore.localizeCapabilities_(
-          event.settingsInfo.capabilities);
+          rawCapabilities);

[dpapad, 2017/05/02 00:07:41]

If we already assert in native_layer.js before triggering the CAPABILITIES_SET
event, this assertion here is redundant. Can we stick with an assertion either
here or in native_layer.js but not in both?

[skau, 2017/05/02 01:52:47]

Done.

       // Special case for PDF printer (until local printers capabilities are
       // reported in CDD format too).
       if (destinationId ==