arc: enable Android tracing in verified-boot mode

chrome/browser/chromeos/arc/trace/arc_trace_bridge.h

+// 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_ARC_TRACE_ARC_TRACE_BRIDGE_H_
+#define CHROME_BROWSER_CHROMEOS_ARC_TRACE_ARC_TRACE_BRIDGE_H_
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/trace_event/trace_event.h"
+#include "chromeos/dbus/arc_trace_agent.h"
+#include "components/arc/arc_service.h"
+#include "components/arc/common/trace.mojom.h"
+#include "components/arc/instance_holder.h"
+
+namespace arc {
+
+class ArcBridgeService;
+
+// This class provides the interface to trigger tracing in the container.
+class ArcTraceBridge : public ArcService,
+                       public chromeos::ArcTraceAgent::ArcTraceBridge,
+                       public InstanceHolder<mojom::TraceInstance>::Observer {
+ public:
+  // Gets the singleton of this class.
+  static ArcTraceBridge* Get();
+
+  explicit ArcTraceBridge(ArcBridgeService* bridge_service);
+  ~ArcTraceBridge() override;
+
+  // InstanceHolder<mojom::TraceInstance>::Observer overrides:
+  void OnInstanceReady() override;
+
+ private:
+  struct Category {
+    // The name used by Android to trigger tracing.
+    const std::string name;
+    // The full name shown in the tracing UI in chrome://tracing.
+    const std::string full_name;
+  };
+  // Query the available categories for tracing.
+  void QueryAvailableCategories();
+
+  // Callback for QueryAvailableCategories.
+  void OnCategoriesReady(const std::vector<std::string>& categories);
+
+  // Callback for StartTracing.
+  void OnTraceStart(bool success);
+
+  // Callback for StopTracing.
+  void OnTraceStop(bool success);
+
+  virtual void StartTracing(

[Luis Héctor Chávez, 2016/12/27 19:15:58]

These two functions are overriden, so they should have the 'override' modifier
instead of 'virtual'.

Also, add

// chromeos::ArcTraceAgent::Delegate overrides:

before both of them (and you can delete the newline that separates them to be
clearer about which functions are the overriden ones).

[shunhsingou, 2016/12/28 09:15:15]

Done.

+      const base::trace_event::TraceConfig& trace_config);
+
+  virtual void StopTracing();
+
+  base::ThreadChecker thread_checker_;

[Luis Héctor Chávez, 2016/12/27 19:15:58]

Since you are in chrome/browser/chromeos, the preferred way of checking if it's
on the right thread is to add

DCHECK_CURRENTLY_ON(BrowserThread::UI);

to the beginning of all methods instead of relying on base::ThredChecker.

[shunhsingou, 2016/12/28 09:15:15]

Done.

+
+  // List of available categories.
+  std::vector<Category> categories_;
+
+  base::WeakPtrFactory<ArcTraceBridge> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcTraceBridge);
+};
+
+}  // namespace arc
+
+#endif  // CHROME_BROWSER_CHROMEOS_ARC_TRACE_ARC_TRACE_BRIDGE_H_