arc: enable Android tracing in verified-boot mode

chrome/browser/chromeos/trace/sys_trace_agent.cc

+// Copyright 2016 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 "chrome/browser/chromeos/trace/sys_trace_agent.h"
+
+#include <string>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "base/trace_event/trace_event.h"
+#include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/dbus/debug_daemon_client.h"
+#include "components/arc/trace/arc_trace_bridge.h"
+
+namespace chromeos {
+
+namespace {
+
+const char kCrosTracingAgentName[] = "cros";

[Luis Héctor Chávez, 2016/10/11 03:38:49]

nit: constexpr.

[shunhsingou, 2016/10/11 07:22:04]

Done.

+const char kCrosTraceLabel[] = "systemTraceEvents";
+
+}  // namespace
+
+std::string SysTraceAgent::GetTracingAgentName() {
+  return kCrosTracingAgentName;
+}
+
+std::string SysTraceAgent::GetTraceEventLabel() {
+  return kCrosTraceLabel;
+}
+
+void SysTraceAgent::StartAgentTracing(
+    const base::trace_event::TraceConfig& trace_config,
+    const StartAgentTracingCallback& callback) {
+  // Starts the system tracing on Chrome OS.
+  // The kernel level tracing is started by debugd via dbus, and the Android
+  // framework level tracing is started via mojo interface (ArcTraceBridge).
+  //
+  // Note that we bind mount /sys/kernel/debug/tracing/trace_marker into the
+  // container during initialization. Therefore, both tracing results will be
+  // collected by debugd from sysfs.
+  chromeos::DebugDaemonClient* debug_daemon =
+      chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
+  if (debug_daemon) {

[Luis Héctor Chávez, 2016/10/11 03:38:48]

nit:

if (!debug_daemon)
  return;

[shunhsingou, 2016/10/11 07:22:05]

Done.

+    // Starts kernel tracing via debugd.
+    debug_daemon->StartAgentTracing(trace_config, callback);
+    LOG(WARNING) << "Tracing ARC Start!!!";

[Luis Héctor Chávez, 2016/10/11 03:38:48]

This does not qualify as a warning. At most it's informative, and it's probably
a candidate for VLOG. Also, try to avoid using "!" in logging statements.

[shunhsingou, 2016/10/11 07:22:05]

Done. It's just for local debugging. Removed.

+    // Starts Android framework tracing via ArcTraceBridge.
+    auto* arc_trace_bridge = arc::ArcTraceBridge::Get();
+    if (arc_trace_bridge) arc_trace_bridge->StartTracing(trace_config);

[Luis Héctor Chávez, 2016/10/11 03:38:49]

nit:

if (!arc_trace_bridge)
  return;

[shunhsingou, 2016/10/11 07:22:04]

Done.

+  }
+}
+
+void SysTraceAgent::StopAgentTracing(

[Luis Héctor Chávez, 2016/10/11 03:38:49]

What thread does this run as? This and the rest of the functions in this class
probably needs thread-checking, like
DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

[shunhsingou, 2016/10/11 07:22:05]

Done.

+    const StopAgentTracingCallback& callback) {
+  chromeos::DebugDaemonClient* debug_daemon =
+      chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
+  debug_daemon->StopAgentTracing(callback);
+
+  LOG(WARNING) << "Tracing ARC Stop!!!";
+  auto* arc_trace_bridge = arc::ArcTraceBridge::Get();
+  if (arc_trace_bridge) arc_trace_bridge->StopTracing();
+}
+
+void SysTraceAgent::SetStopAgentTracingTaskRunner(
+    scoped_refptr<base::TaskRunner> task_runner) {
+  chromeos::DebugDaemonClient* debug_daemon =
+      chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
+  debug_daemon->SetStopAgentTracingTaskRunner(task_runner);
+}
+
+SysTraceAgent* SysTraceAgent::GetInstance() {
+  return base::Singleton<SysTraceAgent>::get();
+}
+
+SysTraceAgent::SysTraceAgent() {}

[Luis Héctor Chávez, 2016/10/11 03:38:48]

nit: = default; same below.

[shunhsingou, 2016/10/11 07:22:05]

Done.

+SysTraceAgent::~SysTraceAgent() {}
+
+}  // namespace chromeos