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

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index 88daf80dcaf5e3e2f22c8a3f7fa8f47575df62f8..4bd4114e0cec6b3fc646356c19bd153dc3029cf8 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -1601,6 +1601,8 @@ void RenderFrameHostImpl::OnRunJavaScriptMessage(
   // process input events.
   GetProcess()->SetIgnoreInputEvents(true);
   render_view_host_->GetWidget()->StopHangMonitorTimeout();
+  render_view_host_->GetWidget()->SetHangMonitorKnownUnresponsive(true);
+  is_within_javascript_dialog_ = true;
   delegate_->RunJavaScriptMessage(this, message, default_prompt,
                                   frame_url, type, reply_msg);
 }
@@ -1613,6 +1615,8 @@ void RenderFrameHostImpl::OnRunBeforeUnloadConfirm(
   // shouldn't process input events.
   GetProcess()->SetIgnoreInputEvents(true);
   render_view_host_->GetWidget()->StopHangMonitorTimeout();
+  render_view_host_->GetWidget()->SetHangMonitorKnownUnresponsive(true);
+  is_within_javascript_dialog_ = true;
   delegate_->RunBeforeUnloadConfirm(this, is_reload, reply_msg);
 }
 
@@ -2414,6 +2418,10 @@ void RenderFrameHostImpl::JavaScriptDialogClosed(
     const base::string16& user_input,
     bool dialog_was_suppressed) {
   GetProcess()->SetIgnoreInputEvents(false);
+  if (is_within_javascript_dialog_) {
+    render_view_host_->GetWidget()->SetHangMonitorKnownUnresponsive(false);
+    is_within_javascript_dialog_ = false;
+  }
   bool is_waiting = is_waiting_for_beforeunload_ack_ || IsWaitingForUnloadACK();
 
   // If we are executing as part of (before)unload event handling, we don't