Fix renderer crash when a file chooser is closed after navigating away from...

chrome/renderer/render_view.cc

Index: chrome/renderer/render_view.cc
===================================================================
--- chrome/renderer/render_view.cc	(revision 12184)
+++ chrome/renderer/render_view.cc	(working copy)
@@ -2608,6 +2608,11 @@
 
 void RenderView::OnFileChooserResponse(
          const std::vector<std::wstring>& file_names) {
+  // This could happen if we navigated to a different page before the user
+  // closed the chooser.
+  if (!file_chooser_.get())
+    return;
+
   file_chooser_->OnFileChoose(file_names);
   file_chooser_.reset();
 }