Fix the content_browsertests everywhere maybe.

chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc

Index: chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
diff --git a/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc b/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
index 261a8fc34ea465d9ac4e54ae9020b3ad463f6cc8..be2c7e84e7fed6fa251388f9dc5bfb9b81a08c7c 100644
--- a/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
+++ b/chrome/browser/ui/app_modal_dialogs/javascript_app_modal_dialog.cc
@@ -10,6 +10,10 @@
 #include "content/public/browser/web_contents_view.h"
 #include "ui/base/text/text_elider.h"
 
+#if defined(USE_AURA)
+#include "ui/aura/root_window.h"
+#endif
+
 using content::JavaScriptDialogCreator;
 using content::WebContents;
 
@@ -80,6 +84,13 @@ JavaScriptAppModalDialog::~JavaScriptAppModalDialog() {
 NativeAppModalDialog* JavaScriptAppModalDialog::CreateNativeDialog() {
   gfx::NativeWindow parent_window =
       web_contents()->GetView()->GetTopLevelNativeWindow();
+#if defined(USE_AURA)
+  if (!parent_window->GetRootWindow()) {
+    // When we are part of a WebContents that isn't actually being displayed on

[Ben Goodger (Google), 2013/01/15 18:19:52]

Does this happen when a js alert happens before a WC is parented even to the
hidden root window?

[Elliot Glaysher, 2013/01/15 19:27:51]

Which hidden root window? AFAIK, there never was one in pure ash builds, and
it's being removed in this patch on the desktop; the hidden root window is part
of the DesktopStackingClient.

+    // the screen, we can't actually attach to it.
+    parent_window = NULL;
+  }
+#endif
   return NativeAppModalDialog::CreateNativeJavaScriptPrompt(this,
                                                             parent_window);
 }