Record Chrome trace events in tcmalloc heap profiles

base/debug/trace_event_system.h

+// Copyright 2013 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 BASE_DEBUG_TRACE_EVENT_SYSTEM_H_
+#define BASE_DEBUG_TRACE_EVENT_SYSTEM_H_
+
+#include "base/base_export.h"
+#include "base/debug/trace_event_impl.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/process/process_metrics.h"
+#include "base/timer/timer.h"
+
+namespace base {
+
+class MessageLoopProxy;
+
+namespace debug {
+
+// Watches for chrome://tracing to be enabled or disabled. When tracing is
+// enabled, also enables system events profiling. This class is the preferred
+// way to turn system tracing on and off.
+class BASE_EXPORT TraceSystemController
+    : public TraceLog::EnabledStateObserver {
+ public:
+  // |message_loop_proxy| must be a proxy to the primary thread for the client
+  // process, e.g. the UI thread in a browser.
+  explicit TraceSystemController(
+      scoped_refptr<MessageLoopProxy> message_loop_proxy);
+  virtual ~TraceSystemController();
+
+  // base::debug::TraceLog::EnabledStateChangedObserver overrides:
+  virtual void OnTraceLogEnabled() OVERRIDE;
+  virtual void OnTraceLogDisabled() OVERRIDE;
+
+  // Starts system profiling.
+  void StartProfiling();
+
+  // Ends system profiling.
+  void StopProfiling();
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(TraceSystemTest, TraceSystemController);
+
+  bool IsTimerRunningForTest() const;
+
+  // Ensures the observer starts and stops tracing on the primary thread.
+  scoped_refptr<MessageLoopProxy> message_loop_proxy_;
+
+  // Timer to schedule system profile dumps.
+  RepeatingTimer<TraceSystemController> dump_timer_;
+
+  WeakPtrFactory<TraceSystemController> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(TraceSystemController);
+};
+
+#ifdef OS_LINUX
+// Converts system memory profiling stats in |input| to
+// trace event compatible JSON and appends to |output|. Visible for testing.
+BASE_EXPORT void AppendSystemProfileAsTraceFormat(SystemMemoryInfoKB *meminfo,
+                                                  std::string* output);
+#endif
+
+}  // namespace debug
+}  // namespace base
+
+#endif  // BASE_DEBUG_TRACE_EVENT_SYSTEM_H_