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..2cfedb67852d46bc1ed5f277e80df7d5faa27898 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 +894,96 @@ 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.

[Dan Beam, 2014/06/20 02:45:17]

@private

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

      * @param {Event} event Event object that contains the option to be
      *     changed and what to set that option.

[ivandavid, 2014/06/20 21:31:45]

Done.

[ivandavid, 2014/06/20 21:31:45]

Done.

+     */
+    onManipulateSettingsForTest_: function(event) {
+      if ('SAVE_AS_PDF' in event.settings) {

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

ALL_CAPS property names look awkward and misleading. Can you name them in a more
conventional way:
selectSaveAsPdfDestination
layoutSettings
pageRange
etc.

[ivandavid, 2014/06/20 21:31:45]

Done.

+        this.destinationStore_.selectDefaultDestination_();

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

Since you added the failure handling logic, check that PDF destination is, in
fact, selected. Some time soon 'default destination' will mean 'default printer
for this computer' and won't be a PDF printer anymore.

Or better yet, do not access private functions here, traverse
this.destinationStore_.destinations() array, find the destination with
print_preview.Destination.GooglePromotedId.SAVE_AS_PDF id and use
this.destinationStore_.selectDestination() to select it.

[ivandavid, 2014/06/20 21:31:44]

Done.

+      } else if ('LAYOUT_SETTINGS' in event.settings) {
+        var element = document.querySelector(
+            event.settings['LAYOUT_SETTINGS'] ?

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

var element = document.querySelector(event.settings.layoutSettings ?

and it begs for a event.settings.layoutSettings.portrait boolean property.

[ivandavid, 2014/06/20 21:31:45]

Done.

+            '.layout-settings-portrait-radio' :
+            '.layout-settings-landscape-radio');
+        if (element) {
+          if (element.clicked) {

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

Crash here will also fail the test, right? Why add more code then?

Same question for all other places checking for undefined controls.

[ivandavid, 2014/06/20 21:31:45]

I am not sure what you mean here. Is the problem that even if an element exists
for a given query, that the clicked property might not actually be defined for
that element, therefore I cannot assume that I can click it?

[Aleksey Shlyapnikov, 2014/06/20 22:13:49]

No, what I mean is the test will crash if you remove this "if (element)" check
and just do "if (element.clicked)", thus removing one level of if statements
from this already pretty deeply nested code. There are a few advantages:
- you still get your test failure;
- less code to maintain
- it matches the module semantics better
Here's why: your code creates an impression that there are valid conditions
under which these elements might not exist (valid in terms of the module, not
your test). It's not true, these elements are always there, they might not be
visible (and you do not care about visibility here), but they are always
accessible. So, your test should just use them and crash if someone renamed the
element's class or changed the behavior is come other way.

+            this.nativeLayer_.previewReady();
+          } else {
+            element.click();
+          }
+        } else {
+          this.nativeLayer_.previewFailed();
+        }
+      } else if ('PAGE_NUMBERS' in event.settings) {
+        var textbox = document.querySelector('.page-settings-custom-input');
+        if (textbox) {
+          if (textbox.value == event.settings['PAGE_NUMBERS']) {

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

event.settings.pageRange

The same for all other settings.

[ivandavid, 2014/06/20 21:31:45]

Done.

+            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'];
+
+            // Triggers the re-rendering of the preview area as
+            // just setting the value isn't sufficient.
+            var radio = document.querySelector(
+                '.page-settings-custom-radio');

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

Fits one line.

[ivandavid, 2014/06/20 21:31:45]

Done.

+            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');

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

It does fit into one line.

[ivandavid, 2014/06/20 21:31:45]

Done.

+        if (checkbox) {
+          if (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');

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

Fits one line.

[ivandavid, 2014/06/20 21:31:45]

Done.

+        if (checkbox) {
+          if (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');

[Aleksey Shlyapnikov, 2014/06/20 17:27:22]

Fits one line.

[ivandavid, 2014/06/20 21:31:45]

Done.

+        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