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

content/browser/tracing/tracing_controller_impl.h

Index: content/browser/tracing/tracing_controller_impl.h
diff --git a/content/browser/tracing/tracing_controller_impl.h b/content/browser/tracing/tracing_controller_impl.h
index 9bd84200d45f276f9c5b84886afa5d9290964818..d051d667d00c59efcc4560f998f37fcec2e680d4 100644
--- a/content/browser/tracing/tracing_controller_impl.h
+++ b/content/browser/tracing/tracing_controller_impl.h
@@ -116,9 +116,9 @@ class TracingControllerImpl : public TracingController {
   void OnCaptureMonitoringSnapshotAcked(
       TraceMessageFilter* trace_message_filter);
 
-  void OnTraceBufferPercentFullReply(
-      TraceMessageFilter* trace_message_filter,
-      float percent_full);
+  void OnTraceBufferPercentFullReply(TraceMessageFilter* trace_message_filter,
+                                     float percent_full,
+                                     size_t buffer_usage);
 
   void OnWatchEventMatched();
 
@@ -152,6 +152,7 @@ class TracingControllerImpl : public TracingController {
   int pending_trace_buffer_percent_full_ack_count_;
   TraceMessageFilterSet pending_trace_buffer_percent_full_filters_;
   float maximum_trace_buffer_percent_full_;
+  size_t total_trace_buffer_usage_;
 
 #if defined(OS_CHROMEOS) || defined(OS_WIN)
   bool is_system_tracing_;