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

content/browser/tracing/tracing_ui.cc

Index: content/browser/tracing/tracing_ui.cc
diff --git a/content/browser/tracing/tracing_ui.cc b/content/browser/tracing/tracing_ui.cc
index 95e3ab92cdec6ce18a5c966dbbcfad86ce97e4e6..44f67467de97af4a482694f9f078c7b61bd5a117 100644
--- a/content/browser/tracing/tracing_ui.cc
+++ b/content/browser/tracing/tracing_ui.cc
@@ -129,9 +129,10 @@ void OnRecordingEnabledAck(const WebUIDataSource::GotDataCallback& callback) {
   callback.Run(res);
 }
 
-void OnTraceBufferPercentFullResult(
-    const WebUIDataSource::GotDataCallback& callback, float result) {
-  std::string str = base::DoubleToString(result);
+void OnTraceBufferUsageResult(const WebUIDataSource::GotDataCallback& callback,
+                              float percent_full,
+                              size_t approximate_event_count) {
+  std::string str = base::DoubleToString(percent_full);
   callback.Run(base::RefCountedString::TakeString(&str));
 }
 
@@ -206,7 +207,7 @@ bool OnBeginJSONRequest(const std::string& path,
   }
   if (path == "json/get_buffer_percent_full") {
     return TracingController::GetInstance()->GetTraceBufferPercentFull(
-        base::Bind(OnTraceBufferPercentFullResult, callback));
+        base::Bind(OnTraceBufferUsageResult, callback));
   }
   if (path == "json/end_recording") {
     return TracingController::GetInstance()->DisableRecording(