[Tracing Clock Sync] Add TracingAgent interface in Chrome

content/browser/tracing/power_tracing_agent.h

Index: content/browser/tracing/power_tracing_agent.h
diff --git a/content/browser/tracing/power_tracing_agent.h b/content/browser/tracing/power_tracing_agent.h
index 3c897d6753df931394354bfeca13814d668feac0..d72b1cb3f57c17d4016b415decaaa635eb6fd33e 100644
--- a/content/browser/tracing/power_tracing_agent.h
+++ b/content/browser/tracing/power_tracing_agent.h
@@ -7,6 +7,7 @@
 
 #include "base/memory/ref_counted_memory.h"
 #include "base/threading/thread.h"
+#include "base/trace_event/tracing_agent.h"
 
 namespace base {
 template <typename Type>
@@ -17,17 +18,24 @@ namespace content {
 
 class BattorPowerTraceProvider;
 
-class PowerTracingAgent {
+class PowerTracingAgent : public base::trace_event::TracingAgent {
  public:
-  typedef base::Callback<void(const scoped_refptr<base::RefCountedString>&)>
-      OutputCallback;
-
-  bool StartTracing();
-  void StopTracing(const OutputCallback& callback);
-
   // Retrieve the singleton instance.
   static PowerTracingAgent* GetInstance();
 
+  // base::trace_event::TracingAgent implementation.
+  std::string GetTracingAgentName() override;
+  std::string GetTraceEventLabel() override;
+
+  bool StartAgentTracing(
+      const base::trace_event::TraceConfig& trace_config) override;
+  void StopAgentTracing(const StopAgentTracingCallback& callback) override;
+
+  bool SupportsExplicitClockSync() override;
+  void RecordClockSyncMarker(
+      int sync_id,
+      const RecordClockSyncMarkerCallback& callback) override;
+
  private:
   // This allows constructor and destructor to be private and usable only
   // by the Singleton class.
@@ -35,12 +43,12 @@ class PowerTracingAgent {
 
   // Constructor.
   PowerTracingAgent();
-  virtual ~PowerTracingAgent();
+  ~PowerTracingAgent() override;
 
-  void OnStopTracingDone(const OutputCallback& callback,
+  void OnStopTracingDone(const StopAgentTracingCallback& callback,
                          const scoped_refptr<base::RefCountedString>& result);
 
-  void FlushOnThread(const OutputCallback& callback);
+  void FlushOnThread(const StopAgentTracingCallback& callback);
 
   scoped_ptr<BattorPowerTraceProvider> battor_trace_provider_;
   bool is_tracing_;