Trace background/visibility events

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index c32da90cff578382833bfbd79524e190e3786065..342f278d1511008b0b351ce751ad4f241ca76292 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -2219,6 +2219,8 @@ void RenderProcessHostImpl::OnDumpHandlesDone() {
 }
 
 void RenderProcessHostImpl::SetBackgrounded(bool backgrounded) {
+  TRACE_EVENT1("renderer_host", "RenderProcessHostImpl::SetBackgrounded",
+               "backgrounded", backgrounded);
   // Note: we always set the backgrounded_ value.  If the process is NULL
   // (and hence hasn't been created yet), we will set the process priority
   // later when we create the process.