Report trace buffer usage as number of events, not only percentage

components/tracing/child_trace_message_filter.h

Index: components/tracing/child_trace_message_filter.h
diff --git a/components/tracing/child_trace_message_filter.h b/components/tracing/child_trace_message_filter.h
index daa00ee3bdad0d8f5b7441c3f005689dbd9f273e..f528dc4be0c9aced00a921bc6f4998f3e2e8e038 100644
--- a/components/tracing/child_trace_message_filter.h
+++ b/components/tracing/child_trace_message_filter.h
@@ -39,7 +39,7 @@ class ChildTraceMessageFilter : public IPC::MessageFilter {
                           const std::string& options);
   void OnDisableMonitoring();
   void OnCaptureMonitoringSnapshot();
-  void OnGetTraceBufferPercentFull();
+  void OnGetTraceBufferUsage();
   void OnSetWatchEvent(const std::string& category_name,
                        const std::string& event_name);
   void OnCancelWatchEvent();