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

content/browser/browser_shutdown_profile_dumper.cc

 // 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.
 
 #include "content/browser/browser_shutdown_profile_dumper.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_impl.h"
@@ skipping 11 matching lines @@
     const base::FilePath& dump_file_name)
     : dump_file_name_(dump_file_name),
       blocks_(0),
       dump_file_(NULL) {
 }
 
 BrowserShutdownProfileDumper::~BrowserShutdownProfileDumper() {
   WriteTracesToDisc();
 }
 
+static float GetTraceBufferPercentFull() {
+  base::debug::TraceLogStatus status =
+      base::debug::TraceLog::GetInstance()->GetStatus();
+  return 100 * static_cast<float>(static_cast<double>(status.event_count) /
+                                  status.event_capacity);
+}
+
 void BrowserShutdownProfileDumper::WriteTracesToDisc() {
   // Note: I have seen a usage of 0.000xx% when dumping - which fits easily.
   // Since the tracer stops when the trace buffer is filled, we'd rather save
   // what we have than nothing since we might see from the amount of events
   // that caused the problem.
-  DVLOG(1) << "Flushing shutdown traces to disc. The buffer is %" <<
-      base::debug::TraceLog::GetInstance()->GetBufferPercentFull() <<
-      " full.";
+  DVLOG(1) << "Flushing shutdown traces to disc. The buffer is "
+           << GetTraceBufferPercentFull() << "% full.";
   DCHECK(!dump_file_);
   dump_file_ = base::OpenFile(dump_file_name_, "w+");
   if (!IsFileValid()) {
     LOG(ERROR) << "Failed to open performance trace file: "
                << dump_file_name_.value();
     return;
   }
   WriteString("{\"traceEvents\":");
   WriteString("[");
 
@@ skipping 83 matching lines @@
 }
 
 void BrowserShutdownProfileDumper::CloseFile() {
   if (!dump_file_)
     return;
   base::CloseFile(dump_file_);
   dump_file_ = NULL;
 }
 
 }  // namespace content