trace event

#include "components/tracing/trace_to_console.h"
#include "components/tracing/trace_config_file.h"
#include "components/tracing/tracing_switches.h"

  // Start startup tracing through TracingController's interface. TraceLog has
  // been enabled in content_main_runner where threads are not available. Now We
  // need to start tracing for all other tracing agents, which require threads.
  if (parsed_command_line_.HasSwitch(switches::kTraceStartup)) {
    base::trace_event::TraceConfig trace_config(
        parsed_command_line_.GetSwitchValueASCII(switches::kTraceStartup),
        base::trace_event::RECORD_UNTIL_FULL);
    TracingController::GetInstance()->StartTracing(
        trace_config,
        TracingController::StartTracingDoneCallback());
  } else if (parsed_command_line_.HasSwitch(switches::kTraceToConsole)) {
      TracingController::GetInstance()->StartTracing(
          tracing::GetConfigForTraceToConsole(),
          TracingController::StartTracingDoneCallback());
  } else if (tracing::TraceConfigFile::GetInstance()->IsEnabled()) {
    // This checks kTraceConfigFile switch.
    TracingController::GetInstance()->StartTracing(
        tracing::TraceConfigFile::GetInstance()->GetTraceConfig(),
        TracingController::StartTracingDoneCallback());
  }