Fix a crash on clicking "Load unpacked extension" multiple times

chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc

Index: chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
diff --git a/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc b/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
index 7a9d112961e869096df1e61ade01ec25ae9821ba..c8b03eabdc6de580437f783194b2f9e85dce6b90 100644
--- a/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
+++ b/chrome/browser/ui/libgtk2ui/select_file_dialog_impl_gtk2.cc
@@ -228,6 +228,10 @@ void SelectFileDialogImplGTK::SelectFileImpl(
   // and chooses 'Open Link in New Tab' when 'Ask where to save each file
   // before downloading.' preference is turned on. (http://crbug.com/29213)
   if (owning_window) {
+    if (IsRunning(owning_window)) {
+      LOG(ERROR) << "Select file dialog already in use!";
+      return;

[Devlin, 2014/12/04 20:00:14]

This isn't what I was referring to.  I meant an early return in the
LoaderHandler, since there's already a dialog up.  I don't think that making a
platform-specific change is the right solution to this.

+    }
     owning_window->AddObserver(this);
     parents_.insert(owning_window);
   }