Trace background/visibility events

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 dfff5e5e77508cb6a8325cf88392c61f865bcc8b..4aef7b88dc79b682aec8f90e772414d16e13c585 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -511,6 +511,7 @@ void RenderWidgetHostImpl::WasHidden() {
   if (is_hidden_)
     return;
 
+  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::WasHidden");
   is_hidden_ = true;
 
   // Don't bother reporting hung state when we aren't active.
@@ -533,6 +534,8 @@ void RenderWidgetHostImpl::WasHidden() {
 void RenderWidgetHostImpl::WasShown(const ui::LatencyInfo& latency_info) {
   if (!is_hidden_)
     return;
+
+  TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::WasShown");
   is_hidden_ = false;
 
   SendScreenRects();