Prevent modal dialogs when preparing to swap out.

chrome/browser/ui/browser_browsertest.cc

Index: chrome/browser/ui/browser_browsertest.cc
diff --git a/chrome/browser/ui/browser_browsertest.cc b/chrome/browser/ui/browser_browsertest.cc
index 686816e1a3334e85a04786456fe0810dc7ccee9f..91f5906a3db02001ebfabc046c6870d0c42ecd70 100644
--- a/chrome/browser/ui/browser_browsertest.cc
+++ b/chrome/browser/ui/browser_browsertest.cc
@@ -472,13 +472,13 @@ IN_PROC_BROWSER_TEST_F(BrowserTest, CrossProcessNavCancelsDialogs) {
   GURL url(test_server()->GetURL("empty.html"));
   ui_test_utils::NavigateToURL(browser(), url);
 
-  // TODO(creis): Test this with a setInterval loop of alert dialogs to ensure
-  // that we can navigate away even if the renderer tries to synchronously
-  // create more.  See http://crbug.com/312490.
+  // Test this with a setInterval loop of alert dialogs to ensure that we can
+  // navigate away even if the renderer tries to synchronously create more.
+  // See http://crbug.com/312490.
   WebContents* contents = browser()->tab_strip_model()->GetActiveWebContents();
   contents->GetRenderViewHost()->ExecuteJavascriptInWebFrame(
       string16(),
-      ASCIIToUTF16("alert('Dialog showing!');"));
+      ASCIIToUTF16("setInterval(\"alert('Dialog showing!');\", 0);"));

[darin (slow to review), 2013/11/01 21:01:42]

This feels like such an imprecise test. I wonder if there is a way to get a more
exact signal for running the dialog.

We already suppress modal alerts generated from unload handlers and after unload
handlers (I presume).

What is the exact sequence of events that needs to happen renderer-side to repro
this bug?

[Charlie Reis, 2013/11/04 19:32:49]

Good point.  I've simplified this to just be two back-to-back dialogs.

The bug is that canceling the first dialog gives the renderer process a chance
to create a new dialog before the SwapOut message arrives.

(I was originally testing with a simple while loop just to generalize a bit, but
then the renderer goes unresponsive (like while(true){}) so I switched to
setInterval.)

   AppModalDialog* alert = ui_test_utils::WaitForAppModalDialog();
   EXPECT_TRUE(alert->IsValid());
   AppModalDialogQueue* dialog_queue = AppModalDialogQueue::GetInstance();