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 8d2390a91305f963ac4fda2f743aedaa71d82852..90afecd8290a9633cee6f2b9de069c68d3f5951a 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -967,6 +967,8 @@ void RenderWidgetHostImpl::ProcessIgnoreInputEventsChanged(
 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())
@@ -976,18 +978,29 @@ 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_) {
+    LogHangMonitorUnresponsive();
+    hang_start_time_ = TimeTicks::Now();
+    if (hang_monitor_timeout_)
+      hang_monitor_timeout_->Restart(hung_renderer_delay_);
+  }
 }
 
 void RenderWidgetHostImpl::StopHangMonitorTimeout() {
+  LogHangMonitorUnresponsive();
+  hang_start_time_ = TimeTicks();
   if (hang_monitor_timeout_)
     hang_monitor_timeout_->Stop();
   RendererIsResponsive();
 }
 
+void RenderWidgetHostImpl::LogHangMonitorUnresponsive() {
+  if (!hang_start_time_.is_null()) {
+    UMA_HISTOGRAM_TIMES("MPArch.RWH_HangMonitorUnresponsive",
+                        TimeTicks::Now() - hang_start_time_);
+  }
+}
+
 void RenderWidgetHostImpl::StartNewContentRenderingTimeout(
     uint32_t next_source_id) {
   current_content_source_id_ = next_source_id;