Reland of Move tracing namespace from base::debug to base::trace_event.

base/trace_event/trace_event_system_stats_monitor.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_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_
 #define BASE_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_
 
 #include "base/base_export.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"
 #include "base/trace_event/trace_event_impl.h"
 
 namespace base {
 
 class SingleThreadTaskRunner;
 
-namespace debug {
+namespace trace_event {
 
 // 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 TraceEventSystemStatsMonitor
     : public TraceLog::EnabledStateObserver {
  public:
   // Length of time interval between stat profiles.
   static const int kSamplingIntervalMilliseconds = 2000;
 
   // |task_runner| must be the primary thread for the client
   // process, e.g. the UI thread in a browser.
   explicit TraceEventSystemStatsMonitor(
       scoped_refptr<SingleThreadTaskRunner> task_runner);
 
   virtual ~TraceEventSystemStatsMonitor();
 
-  // base::debug::TraceLog::EnabledStateChangedObserver overrides:
+  // base::trace_event::TraceLog::EnabledStateChangedObserver overrides:
   void OnTraceLogEnabled() override;
   void OnTraceLogDisabled() override;
 
   // Retrieves system profiling at the current time.
   void DumpSystemStats();
 
  private:
   FRIEND_TEST_ALL_PREFIXES(TraceSystemStatsMonitorTest,
                            TraceEventSystemStatsMonitor);
 
@@ skipping 13 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(TraceEventSystemStatsMonitor);
 };
 
 // Converts system memory profiling stats in |input| to
 // trace event compatible JSON and appends to |output|. Visible for testing.
 BASE_EXPORT void AppendSystemProfileAsTraceFormat(const SystemMetrics&
                                                   system_stats,
                                                   std::string* output);
 
-}  // namespace debug
+}  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_SYSTEM_STATS_MONITOR_H_