Fix all remaining print preview closure compiler errors

chrome/test/data/webui/print_preview.js

Index: chrome/test/data/webui/print_preview.js
diff --git a/chrome/test/data/webui/print_preview.js b/chrome/test/data/webui/print_preview.js
index d01c54386aa7e1136bc30143b09c7c7f751aa252..3f24bb3e9d49ac32afa8c88205e10012bba71fd9 100644
--- a/chrome/test/data/webui/print_preview.js
+++ b/chrome/test/data/webui/print_preview.js
@@ -18,6 +18,11 @@ function PrintPreviewWebUITest() {
   this.previewArea_ = null;
 }
 
+/**
+ * Instance of PrintPreview for the test.
+ */
+var printPreview;
+
 /**
  * Index of the "Save as PDF" printer.
  * @type {number}
@@ -81,6 +86,7 @@ PrintPreviewWebUITest.prototype = {
    */
   preLoad: function() {
     window.addEventListener('DOMContentLoaded', function() {
+      print_preview.IsWebUITest = true;

[dpapad, 2017/05/08 23:39:48]

We are adding a DOMContentLoaded handler here, and also one in print_preview
prod code, and we rely on the order that the two listeners execute (first one
sets a boolean, second one reads the boolean).

I think this is a bit fragile. Probably better to undo this change for now and
just leave the global "var printPriview" variable in the prod code and add a
comment that the reference is used by tests.

[rbpotter, 2017/05/09 00:08:52]

Done.

       function NativeLayerStub() {
         cr.EventTarget.call(this);
         this.printStarted_ = false;
@@ -119,6 +125,9 @@ PrintPreviewWebUITest.prototype = {
           function() {
         return false;
       };
+      printPreview = new print_preview.PrintPreview();
+      printPreview.initialize();
+
     }.bind(this));
   },
 
@@ -626,7 +635,6 @@ TEST_F('PrintPreviewWebUITest', 'SourceIsHTMLCapabilities', function() {
     checkElementDisplayed(rasterize, false);
   checkSectionVisible(mediaSize, false);
   checkSectionVisible(scalingSettings, false);
-
   this.expandMoreSettings();
 
   checkElementDisplayed(fitToPage, false);
@@ -634,7 +642,6 @@ TEST_F('PrintPreviewWebUITest', 'SourceIsHTMLCapabilities', function() {
     checkElementDisplayed(rasterize, false);
   checkSectionVisible(mediaSize, true);
   checkSectionVisible(scalingSettings, true);
-
   this.waitForAnimationToEnd('more-settings');
 });