[Tracing Clock Sync] Add TracingAgent interface in Chrome

content/public/browser/tracing_controller.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 CONTENT_PUBLIC_BROWSER_TRACING_CONTROLLER_H_
 #define CONTENT_PUBLIC_BROWSER_TRACING_CONTROLLER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 20 matching lines @@
   // is passed to either DisableTracing() or CaptureMonitoringSnapshot() and
   // receives the trace data followed by a notification that all child processes
   // have completed tracing and the data collection is over.
   // All methods are called on the UI thread.
   // Close method will be called exactly once and no methods will be
   // called after that.
   class CONTENT_EXPORT TraceDataSink
       : public base::RefCountedThreadSafe<TraceDataSink> {
    public:
     virtual void AddTraceChunk(const std::string& chunk) {}
-    virtual void SetSystemTrace(const std::string& data) {}
+
+    virtual void AddAdditionalTracingAgentTrace(const std::string& agent_name,

[shatch, 2015/11/27 19:29:18]

nit: Long name, maybe just AddAgentTrace?

[Zhen Wang, 2015/12/01 00:14:32]

Done.

+                                                const std::string& trace_data);
+    virtual const base::DictionaryValue& GetAdditionalTracingAgentTrace() const;
 
     // Notice that TracingController adds some default metadata when
     // DisableRecording is called, which may override metadata that you would
     // set beforehand in case of key collision.
     virtual void AddMetadata(const base::DictionaryValue& data);
     virtual const base::DictionaryValue& GetMetadata() const;
-    // TODO(prabhur) Replace all the Set* functions with a generic function:
-    // TraceDataSink::AppendAdditionalData(const std::string& name,
-    // const std::string& trace_data)
-    virtual void SetPowerTrace(const std::string& data) {}
+
     virtual void Close() {}
 
    protected:
     friend class base::RefCountedThreadSafe<TraceDataSink>;
     virtual ~TraceDataSink() {}
 
    private:
+    base::DictionaryValue additional_tracing_agent_trace_;

[shatch, 2015/11/27 19:29:18]

Why not just a std::map?

[Zhen Wang, 2015/12/01 00:14:32]

Done.

     base::DictionaryValue metadata_;
   };
 
   // An implementation of this interface is passed when constructing a
   // TraceDataSink, and receives chunks of the final trace data as it's being
   // constructed.
   // Methods may be called from any thread.
   class CONTENT_EXPORT TraceDataEndpoint
       : public base::RefCountedThreadSafe<TraceDataEndpoint> {
    public:
@@ skipping 156 matching lines @@
   // Check if the tracing system is tracing
   virtual bool IsTracing() const = 0;
 
  protected:
   virtual ~TracingController() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_TRACING_CONTROLLER_H_