Adds a callback to TracingAgent::StartAgentTracing()

content/browser/tracing/etw_system_event_consumer_win.cc

 // Copyright 2014 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/tracing/etw_system_event_consumer_win.h"
 
 #include <stdint.h>
 
 #include "base/base64.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/lazy_instance.h"
 #include "base/memory/singleton.h"
 #include "base/strings/stringprintf.h"
+#include "base/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event_impl.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace content {
 
 namespace {
 
 const char kETWTracingAgentName[] = "etw";
 const char kETWTraceLabel[] = "systemTraceEvents";
@@ skipping 18 matching lines @@
 }
 
 std::string EtwSystemEventConsumer::GetTracingAgentName() {
   return kETWTracingAgentName;
 }
 
 std::string EtwSystemEventConsumer::GetTraceEventLabel() {
   return kETWTraceLabel;
 }
 
-bool EtwSystemEventConsumer::StartAgentTracing(
-    const base::trace_event::TraceConfig& trace_config) {
+void EtwSystemEventConsumer::StartAgentTracing(
+    const base::trace_event::TraceConfig& trace_config,
+    const StartAgentTracingCallback& callback) {
   // Activate kernel tracing.
-  if (!StartKernelSessionTracing())
-    return false;
+  if (!StartKernelSessionTracing()) {
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE,
+        base::Bind(callback, GetTracingAgentName(), false /* success */));
+    return;
+  }
 
   // Start the consumer thread and start consuming events.
   thread_.Start();
   thread_.message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&EtwSystemEventConsumer::TraceAndConsumeOnThread,
                  base::Unretained(this)));
 
-  return true;
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::Bind(callback, GetTracingAgentName(), true /* success */));
 }
 
 void EtwSystemEventConsumer::StopAgentTracing(
     const StopAgentTracingCallback& callback) {
   // Deactivate kernel tracing.
   if (!StopKernelSessionTracing()) {
     LOG(FATAL) << "Could not stop system tracing.";
   }
 
   // Stop consuming and flush events.
@@ skipping 162 matching lines @@
       base::RefCountedString::TakeString(&output);
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&EtwSystemEventConsumer::OnStopSystemTracingDone,
                  base::Unretained(this),
                  callback,
                  result));
 }
 
 }  // namespace content