Added basic browser test for window.print() from Chrome apps.

chrome/browser/ui/webui/print_preview/print_preview_ui.cc

Index: chrome/browser/ui/webui/print_preview/print_preview_ui.cc
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_ui.cc b/chrome/browser/ui/webui/print_preview/print_preview_ui.cc
index ca4c7e43595e953969fe7512ee9086d07136a4f2..58cf9efa7ae9c36fc0efee4035c3178e5ae2f2f2 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_ui.cc
+++ b/chrome/browser/ui/webui/print_preview/print_preview_ui.cc
@@ -520,8 +520,12 @@ void PrintPreviewUI::OnPreviewDataIsAvailable(int expected_pages_count,
   }
   base::FundamentalValue ui_identifier(id_);
   base::FundamentalValue ui_preview_request_id(preview_request_id);
-  web_ui()->CallJavascriptFunction("updatePrintPreview", ui_identifier,
-                                   ui_preview_request_id);
+  if (AutoCancelForTesting()) {

[Vitaly Buka (NO REVIEWS), 2013/08/29 00:10:25]

Is possible to avoid js chages and just call OnHidePreviewDialog() here?

[dharcourt, 2013/08/29 04:02:02]

Calling OnHidePreviewDialog() doesn't work (the tests time out), but calling
OnClosePrintPreviewDialog() does :-).

I followed the code and the only significant thing that print_preview.js's
close_() does in the context of the test is OnClosePrintPreviewDialog(), so I
was able to back out all JavaScript changes. Thanks!

+    web_ui()->CallJavascriptFunction("autoCancelPrintPreviewForTesting");
+  } else {
+    web_ui()->CallJavascriptFunction("updatePrintPreview", ui_identifier,
+                                     ui_preview_request_id);
+  }
 }
 
 void PrintPreviewUI::OnPrintPreviewDialogDestroyed() {
@@ -582,3 +586,14 @@ void PrintPreviewUI::OnReloadPrintersList() {
 void PrintPreviewUI::OnPrintPreviewScalingDisabled() {
   web_ui()->CallJavascriptFunction("printScalingDisabledForSourcePDF");
 }
+
+static bool auto_cancel_for_testing_ = false;

[Vitaly Buka (NO REVIEWS), 2013/08/28 01:20:26]

auto_cancel_for_testing_ -> g_auto_cancel_for_testing

[dharcourt, 2013/08/28 23:23:57]

Done, thanks.

+
+void PrintPreviewUI::SetAutoCancelForTesting(bool auto_cancel) {
+  auto_cancel_for_testing_ = auto_cancel;
+}
+
+bool PrintPreviewUI::AutoCancelForTesting() {
+  return auto_cancel_for_testing_;
+}
+