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

content/public/browser/tracing_controller.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_BROWSER_TRACING_CONTROLLER_H_
 #define CONTENT_PUBLIC_BROWSER_TRACING_CONTROLLER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 143 matching lines @@
   // request, TracingFileResultCallback will be called back with a file that
   // contains the traced data.
   //
   // If |trace_data_sink| is not null, it will receive chunks of trace data
   // as a comma-separated sequences of JSON-stringified events, followed by
   // a notification that the trace collection is finished.
   virtual bool CaptureMonitoringSnapshot(
       const scoped_refptr<TraceDataSink>& trace_data_sink) = 0;
 
   // Get the maximum across processes of trace buffer percent full state.
-  // When the TraceBufferPercentFull value is determined, the callback is
+  // When the TraceBufferUsage value is determined, the callback is
   // called.
-  typedef base::Callback<void(float)> GetTraceBufferPercentFullCallback;
-  virtual bool GetTraceBufferPercentFull(
-      const GetTraceBufferPercentFullCallback& callback) = 0;
+  typedef base::Callback<void(float, size_t)> GetTraceBufferUsageCallback;
+  virtual bool GetTraceBufferUsage(
+      const GetTraceBufferUsageCallback& callback) = 0;
 
   // |callback| will will be called every time the given event occurs on any
   // process.
   typedef base::Callback<void()> WatchEventCallback;
   virtual bool SetWatchEvent(const std::string& category_name,
                              const std::string& event_name,
                              const WatchEventCallback& callback) = 0;
 
   // Cancel the watch event. If tracing is enabled, this may race with the
   // watch event callback.
   virtual bool CancelWatchEvent() = 0;
 
  protected:
   virtual ~TracingController() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_TRACING_CONTROLLER_H_