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..4e8e8abcd79cf28ae2403723f3c12de54919c4f3 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()) {
+    OnClosePrintPreviewDialog();
+  } else {
+    web_ui()->CallJavascriptFunction("updatePrintPreview", ui_identifier,
+                                     ui_preview_request_id);
+  }
 }
 
 void PrintPreviewUI::OnPrintPreviewDialogDestroyed() {
@@ -582,3 +586,13 @@ void PrintPreviewUI::OnReloadPrintersList() {
 void PrintPreviewUI::OnPrintPreviewScalingDisabled() {
   web_ui()->CallJavascriptFunction("printScalingDisabledForSourcePDF");
 }
+
+static bool g_auto_cancel_for_testing_ = false;
+
+void PrintPreviewUI::SetAutoCancelForTesting(bool auto_cancel) {
+  g_auto_cancel_for_testing_ = auto_cancel;
+}
+
+bool PrintPreviewUI::AutoCancelForTesting() {
+  return g_auto_cancel_for_testing_;
+}