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

chrome/browser/resources/print_preview/native_layer.js

Index: chrome/browser/resources/print_preview/native_layer.js
diff --git a/chrome/browser/resources/print_preview/native_layer.js b/chrome/browser/resources/print_preview/native_layer.js
index efdd55b36073695ca5a34c475a299e408e7ea0a9..5040f3b3c9b1475fab2139e3bc36acbb80165e24 100644
--- a/chrome/browser/resources/print_preview/native_layer.js
+++ b/chrome/browser/resources/print_preview/native_layer.js
@@ -46,6 +46,7 @@ cr.define('print_preview', function() {
     global['onPrivetCapabilitiesSet'] =
         this.onPrivetCapabilitiesSet_.bind(this);
     global['onPrivetPrintFailed'] = this.onPrivetPrintFailed_.bind(this);
+    global['onClickStuff'] = this.onClickStuff_.bind(this);
   };
 
   /**
@@ -77,7 +78,8 @@ cr.define('print_preview', function() {
     PRIVET_PRINTER_CHANGED: 'print_preview.NativeLayer.PRIVET_PRINTER_CHANGED',
     PRIVET_CAPABILITIES_SET:
         'print_preview.NativeLayer.PRIVET_CAPABILITIES_SET',
-    PRIVET_PRINT_FAILED: 'print_preview.NativeLayer.PRIVET_PRINT_FAILED'
+    PRIVET_PRINT_FAILED: 'print_preview.NativeLayer.PRIVET_PRINT_FAILED',
+    CLICK_STUFF: 'print_preview.NativeLayer.CLICK_STUFF'
   };
 
   /**
@@ -672,6 +674,15 @@ cr.define('print_preview', function() {
             new Event(NativeLayer.EventType.PRIVET_PRINT_FAILED);
       privetPrintFailedEvent.httpError = http_error;
       this.dispatchEvent(privetPrintFailedEvent);
+    },
+
+    /**
+     * Function call from browsertest to start clicking certain buttons
+     */
+    onClickStuff_: function() {
+      var clickStuffEvent =
+          new Event(NativeLayer.EventType.CLICK_STUFF);
+      this.dispatchEvent(clickStuffEvent);
     }
   };