Added a test that currently is able to print to pdf.

chrome/browser/resources/print_preview/print_preview.js

Index: chrome/browser/resources/print_preview/print_preview.js
diff --git a/chrome/browser/resources/print_preview/print_preview.js b/chrome/browser/resources/print_preview/print_preview.js
index ac3a0ab789135db2746d6fe3b522398b759867d9..70bfeaf241abaf8b9b82091cd018b1219169586a 100644
--- a/chrome/browser/resources/print_preview/print_preview.js
+++ b/chrome/browser/resources/print_preview/print_preview.js
@@ -285,7 +285,10 @@ cr.define('print_preview', function() {
           this.nativeLayer_,
           print_preview.NativeLayer.EventType.PRIVET_PRINT_FAILED,
           this.onPrivetPrintFailed_.bind(this));
-
+      this.tracker.add(
+          this.nativeLayer_,
+          print_preview.NativeLayer.EventType.MANIPULATE_SETTINGS,
+          this.onManipulateSettings_.bind(this));
 
       this.tracker.add(
           $('system-dialog-link'),
@@ -691,6 +694,7 @@ cr.define('print_preview', function() {
     onPreviewGenerationDone_: function() {
       this.isPreviewGenerationInProgress_ = false;
       this.printHeader_.isPrintButtonEnabled = true;
+      chrome.send('UILoaded');
       this.printIfReady_();
     },
 
@@ -889,6 +893,16 @@ cr.define('print_preview', function() {
         localStrings.getString('couldNotPrint'));
     },
 
+    onManipulateSettings_: function() {
+      var settings = $('layout-settings');
+      this.destinationStore_.selectDefaultDestination_();
+      var portrait = document.getElementsByClassName(
+          'layout-settings-landscape-radio')[0];
+      if (portrait) {
+        portrait.click();
+      }
+    },
+
     /**
      * Called when the open-cloud-print-dialog link is clicked. Opens the Google
      * Cloud Print web dialog.