Hang Monitor UMA

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 ea1cac8a5370887ea9fc37db2f0311b55cbc767c..5eaa53cef4f593e56f2cadbb90b61d780e024512 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -961,6 +961,8 @@ bool RenderWidgetHostImpl::ScheduleComposite() {
 void RenderWidgetHostImpl::StartHangMonitorTimeout(
     base::TimeDelta delay,
     blink::WebInputEvent::Type event_type) {
+  if (hang_start_time_.is_null())
+    hang_start_time_ = TimeTicks::Now();
   if (!hang_monitor_timeout_)
     return;
   if (!hang_monitor_timeout_->IsRunning())
@@ -970,10 +972,14 @@ void RenderWidgetHostImpl::StartHangMonitorTimeout(
 }
 
 void RenderWidgetHostImpl::RestartHangMonitorTimeoutIfNecessary() {
-  if (!hang_monitor_timeout_)
-    return;
-  if (in_flight_event_count_ > 0 && !is_hidden_)
-    hang_monitor_timeout_->Restart(hung_renderer_delay_);
+  if (in_flight_event_count_ > 0 && !is_hidden_) {
+    if (!hang_start_time_.is_null())

[Ilya Sherman, 2017/03/24 21:16:19]

nit: Please use curly braces, since the body of this if-stmt spans multiple
lines of text.

+      UMA_HISTOGRAM_TIMES("MPArch.RWH_HangMonitorUnresponsive",
+                          TimeTicks::Now() - hang_start_time_);
+    hang_start_time_ = TimeTicks::Now();
+    if (hang_monitor_timeout_)
+      hang_monitor_timeout_->Restart(hung_renderer_delay_);
+  }
 }
 
 void RenderWidgetHostImpl::DisableHangMonitorForTesting() {
@@ -982,6 +988,10 @@ void RenderWidgetHostImpl::DisableHangMonitorForTesting() {
 }
 
 void RenderWidgetHostImpl::StopHangMonitorTimeout() {
+  if (!hang_start_time_.is_null())
+    UMA_HISTOGRAM_TIMES("MPArch.RWH_HangMonitorUnresponsive",
+                        TimeTicks::Now() - hang_start_time_);
+  hang_start_time_ = TimeTicks();

[Ilya Sherman, 2017/03/24 21:16:19]

Could you please factor out these four lines of shared code into a small helper
function?

   if (hang_monitor_timeout_)
     hang_monitor_timeout_->Stop();
   RendererIsResponsive();