[Tracing Clock Sync] Add TracingAgent interface in Chrome

content/public/browser/tracing_controller.h

Index: content/public/browser/tracing_controller.h
diff --git a/content/public/browser/tracing_controller.h b/content/public/browser/tracing_controller.h
index 6467e95212fbb3a2c976274cf920154c81918773..13ab3ac813e45a7631b87cf53d190013f4ddfc8c 100644
--- a/content/public/browser/tracing_controller.h
+++ b/content/public/browser/tracing_controller.h
@@ -38,17 +38,17 @@ class TracingController {
       : 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:
@@ -56,6 +56,7 @@ class TracingController {
     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_;
   };