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..954ffae8cca562443288b3f55b2087536e57659b 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['onManipulateSettings'] = this.onManipulateSettings_.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',
+    MANIPULATE_SETTINGS: 'print_preview.NativeLayer.MANIPULATE_SETTINGS'
   };
 
   /**
@@ -672,6 +674,33 @@ 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
+     */
+    onManipulateSettings_: function(messageName, parameter) {

[ivandavid, 2014/06/17 21:38:18]

'messageName' is the property of print preview that I want to change and
parameter is what I actually want to change it to.

[Lei Zhang, 2014/06/17 21:57:33]

You should update the JS doc, rather than mentioning it in a code review
comment.

[ivandavid, 2014/06/17 22:59:16]

Done. I think I correctly followed the @param section, however I am not sure,
since |parameter| can be different types. So I listed all the possible types and
the situations in which |parameter| would be of that type.

+      var manipulateSettingsEvent =
+          new Event(NativeLayer.EventType.MANIPULATE_SETTINGS);
+      manipulateSettingsEvent.messageName = messageName;
+      if (messageName == 'SAVE_AS_PDF') {
+      }
+      else if (messageName == 'LAYOUT_SETTINGS') {
+        manipulateSettingsEvent.layoutSettings = parameter;
+      }
+      else if (messageName == 'PAGE_NUMBERS') {
+        manipulateSettingsEvent.pageNumbers = parameter;
+      }
+      else if (messageName == 'HEADERS_AND_FOOTERS') {
+        manipulateSettingsEvent.headersAndFooters = parameter;
+      }
+      else if (messageName == 'BACKGROUND_COLORS_AND_IMAGES') {
+        manipulateSettingsEvent.backgroundColorsAndImages = parameter;
+      }
+      else if (messageName == 'MARGINS') {
+        manipulateSettingsEvent.margins = parameter;
+      }
+      this.dispatchEvent(manipulateSettingsEvent);
     }
   };