Don't wait to close tabs waiting for JavaScript dialogs.

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index 943b1cc920129c011fed4b6b27b1764749f8b030..0329469ac8727ed79bb0d6e2af91e4205f067871 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -936,6 +936,9 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // PlzNavigate: all navigations require a beforeUnload ACK.
   bool unload_ack_is_for_navigation_;
 
+  // True while a JavaScript dialog is shown.
+  bool is_within_javascript_dialog_ = false;

[Charlie Reis, 2016/10/05 22:00:59]

Any chance the delegate knows if the dialog is showing, and we can just ask it
instead?  I'm not opposed to adding this bit if needed, but it would be nice to
avoid having even more state on RFH if possible.

+
   // Indicates whether this RenderFrameHost is in the process of loading a
   // document or not.
   bool is_loading_;