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..d2b014ff5e3cfad847fbb46a39e4d704b627ea52 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_FOR_TEST,
+          this.onManipulateSettingsForTest_.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;
+      this.nativeLayer_.previewReady();
       this.printIfReady_();
     },
 
@@ -890,6 +894,97 @@ cr.define('print_preview', function() {
     },
 
     /**
+     * Called when the print preview settings need to be changed for testing.
+     * @param {Event} event Event object that contains that option that is to
+     *     be changed and what to set that option.
+     */
+    onManipulateSettingsForTest_: function(event) {
+      if ('SAVE_AS_PDF' in event.settings) {
+        this.destinationStore_.selectDefaultDestination_();
+      } else if ('LAYOUT_SETTINGS' in event.settings) {
+        var element = document.querySelector(
+            event.settings['LAYOUT_SETTINGS'] ?
+            '.layout-settings-portrait-radio' :
+            '.layout-settings-landscape-radio');
+        if (element) {
+          if (element.clicked) {
+            this.nativeLayer_.previewReady();
+          } else {
+            element.click();
+          }
+        } else {
+          this.nativeLayer_.previewFailed();
+        }
+      } else if ('PAGE_NUMBERS' in event.settings) {

[ivandavid, 2014/06/20 01:00:26]

Rewrote the whole section because it wasn't working when I actually tested it.
Now it works correctly and can accept formatted strings.

+        var textbox = document.querySelector('.page-settings-custom-input');
+        if (textbox) {
+          if (textbox.value == event.settings['PAGE_NUMBERS']) {
+            this.nativeLayer_.previewReady();
+          } else {
+            // Assuming that the string format is correct for now.
+            // TODO: Will need a way to validate it just so the test doesn't
+            //    hang mysteriously if the string isn't correct.
+            textbox.value = event.settings['PAGE_NUMBERS'];
+            var radio = document.querySelector(
+                '.page-settings-custom-radio');
+            if (radio) {
+              radio.click();
+            } else {
+              this.nativeLayer_.previewFailed();
+            }
+          }
+        } else {
+          this.nativeLayer_.previewFailed();
+        }
+      } else if ('HEADERS_AND_FOOTERS' in event.settings) {
+        var checkbox = document.querySelector(
+            '.header-footer-checkbox');
+        if (checkbox) {
+          if ((event.settings['HEADERS_AND_FOOTERS'] && checkbox.checked) ||
+               (!event.settings['HEADERS_AND_FOOTERS'] && !checkbox.checked)) {
+            this.nativeLayer_.previewReady();
+          } else {
+            checkbox.click();
+          }
+        } else {
+          this.nativeLayer_.previewFailed();
+        }
+      } else if ('BACKGROUND_COLORS_AND_IMAGES' in event.settings) {
+        var checkbox = document.querySelector(
+            '.css-background-checkbox');
+        if (checkbox) {
+          if ((event.settings['BACKGROUND_COLORS_AND_IMAGES'] &&
+              checkbox.checked) ||
+              (!event.settings['BACKGROUND_COLORS_AND_IMAGES'] &&
+              !checkbox.checked)) {
+            this.nativeLayer_.previewReady();
+          } else {
+            checkbox.click();
+          }
+        } else {
+          this.nativeLayer_.previewFailed();
+        }
+      } else if ('MARGINS' in event.settings) {
+        var element =
+            document.querySelector('.margin-settings-select');
+        var index = parseInt(event.margins, 10);
+        if (element) {
+          if (event.settings['MARGINS'] == element.selectedIndex) {
+            this.nativeLayer_.previewReady();
+          } else if (event.settings['MARGINS'] >= 0 &&
+                     event.settings['MARGINS'] < element.length) {
+            element.selectedIndex = event.settings['MARGINS'];
+            this.marginSettings_.onSelectChange_();
+          } else {
+            this.nativeLayer_.previewFailed();
+          }
+        } else {
+          this.nativeLayer_.previewFailed();
+        }
+      }
+    },
+
+    /**
      * Called when the open-cloud-print-dialog link is clicked. Opens the Google
      * Cloud Print web dialog.
      * @private