Prevent hang monitor restarts when hidden

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 727a14ba9ad1d687441e5f590890d170c6f8dddd..da12c76ef0355de5b1840b35dc28d8a92d899ae1 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -864,11 +864,15 @@ bool RenderWidgetHostImpl::ScheduleComposite() {
 }
 
 void RenderWidgetHostImpl::StartHangMonitorTimeout(base::TimeDelta delay) {
+  if (is_hidden_)
+    return;

[piman, 2015/02/19 23:43:52]

Do we need to restart it when we go visible (i.e. keep around the state that we
want it running), or does it not matter?

[jdduke (slow), 2015/02/23 16:03:26]

Good question, and I don't really have the answer. I think ideally the answer is
yes, but this change is simply making our decision to turn the timeout off
consistent when the widget is hidden.

I'm a little hesitant to make that behavior change now, given how fragile this
has been, but I think we should look into it. I'll file a bug and note it here.

   if (hang_monitor_timeout_)
     hang_monitor_timeout_->Start(delay);
 }
 
 void RenderWidgetHostImpl::RestartHangMonitorTimeout() {
+  if (is_hidden_)
+    return;
   if (hang_monitor_timeout_)
     hang_monitor_timeout_->Restart(
         base::TimeDelta::FromMilliseconds(hung_renderer_delay_ms_));