arc: enable Android tracing in verified-boot mode

chromeos/trace/arc_trace_agent.h

+// Copyright 2017 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 CHROMEOS_TRACE_ARC_TRACE_AGENT_H_
+#define CHROMEOS_TRACE_ARC_TRACE_AGENT_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/tracing_agent.h"
+#include "chromeos/chromeos_export.h"
+
+namespace chromeos {
+
+// A wrapper for controlling tracing in ARC container.
+class CHROMEOS_EXPORT ArcTraceAgent : public base::trace_event::TracingAgent {
+ public:
+  class Delegate {
+   public:
+    typedef base::Callback<void(bool)> StartTracingCallback;

[Luis Héctor Chávez, 2017/01/18 17:31:32]

Is there any reason you're using typedef instead of using like I requested?
using is preferred in Chromium code:
https://chromium-cpp.appspot.com/#core-whitelist

[Earl Ou, 2017/01/25 03:50:59]

Done. Changed to using.

+    typedef base::Callback<void(const std::string&)> StopTracingCallback;
+
+    ~Delegate() = default;

[Yusuke Sato, 2017/01/19 23:06:19]

virtual

[Earl Ou, 2017/01/25 03:50:59]

Done.

+
+    virtual void StartTracing(
+        const base::trace_event::TraceConfig& trace_config,
+        const StartTracingCallback& callback) = 0;
+
+    virtual void StopTracing(const StopTracingCallback& callback) = 0;
+  };
+
+  virtual ~ArcTraceAgent() = default;
+
+  static ArcTraceAgent* GetInstance();
+
+  // Sets Delegate instance, which should implement the communication
+  // using ARC bridge. If set to nullptr, calling of Start/StopAgentTracing
+  // does nothing.
+  virtual void SetDelegate(Delegate* delegate) = 0;
+};
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_TRACE_ARC_TRACE_AGENT_H_