[Tracing Clock Sync] Add TracingAgent interface in Chrome

content/browser/tracing/tracing_controller_impl_data_sinks.cc

Index: content/browser/tracing/tracing_controller_impl_data_sinks.cc
diff --git a/content/browser/tracing/tracing_controller_impl_data_sinks.cc b/content/browser/tracing/tracing_controller_impl_data_sinks.cc
index 0f67ac357bd057f29787a08de0355df40d8493f0..396847a5edce6fa3328f93d2638670892c379d45 100644
--- a/content/browser/tracing/tracing_controller_impl_data_sinks.cc
+++ b/content/browser/tracing/tracing_controller_impl_data_sinks.cc
@@ -116,10 +116,13 @@ class StringTraceDataSink : public TracingController::TraceDataSink {
 
   void AddTraceChunk(const std::string& chunk) override {
     std::string trace_string;
-    if (trace_.empty())
-      trace_string = "{\"traceEvents\":[";
-    else
+    if (trace_.empty()) {
+      trace_string = "{\"" +
+          std::string(base::trace_event::TracingAgent::kChromeTraceLabel) +
+          "\":[";
+    } else {
       trace_string = ",";
+    }
     trace_string += chunk;
 
     AddTraceChunkAndPassToEndpoint(trace_string);
@@ -131,24 +134,18 @@ class StringTraceDataSink : public TracingController::TraceDataSink {
     endpoint_->ReceiveTraceChunk(chunk);
   }
 
-  void SetSystemTrace(const std::string& data) override {
-    system_trace_ = data;
-  }
-
-  void SetPowerTrace(const std::string& data) override { power_trace_ = data; }
-
   void Close() override {
     AddTraceChunkAndPassToEndpoint("]");
-    if (!system_trace_.empty())
-      AddTraceChunkAndPassToEndpoint(",\"systemTraceEvents\": " +
-                                     system_trace_);
+
+    for (auto const &it : GetAdditionalTracingAgentTrace())
+      AddTraceChunkAndPassToEndpoint(",\"" + it.first + "\": " + it.second);
+
     std::string metadataJSON;
     if (base::JSONWriter::Write(GetMetadata(), &metadataJSON) &&
-        !metadataJSON.empty())
-      AddTraceChunkAndPassToEndpoint(",\"metadata\": " + metadataJSON);
-    if (!power_trace_.empty()) {
-      AddTraceChunkAndPassToEndpoint(",\"powerTraceAsString\": " +
-                                     power_trace_);
+        !metadataJSON.empty()) {
+      AddTraceChunkAndPassToEndpoint(",\"" +
+          std::string(base::trace_event::TracingAgent::kMetadataTraceLabel) +
+          "\": " + metadataJSON);
     }
 
     AddTraceChunkAndPassToEndpoint("}");
@@ -162,8 +159,6 @@ class StringTraceDataSink : public TracingController::TraceDataSink {
 
   scoped_refptr<TracingController::TraceDataEndpoint> endpoint_;
   std::string trace_;
-  std::string system_trace_;
-  std::string power_trace_;
 
   DISALLOW_COPY_AND_ASSIGN(StringTraceDataSink);
 };
@@ -184,12 +179,6 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
                    this, chunk_ptr));
   }
 
-  void SetSystemTrace(const std::string& data) override {
-    system_trace_ = data;
-  }
-
-  void SetPowerTrace(const std::string& data) override { power_trace_ = data; }
-
   void Close() override {
     BrowserThread::PostTask(
         BrowserThread::FILE, FROM_HERE,
@@ -226,10 +215,13 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
       const scoped_refptr<base::RefCountedString> chunk_ptr) {
     DCHECK_CURRENTLY_ON(BrowserThread::FILE);
     std::string trace;
-    if (compressed_trace_data_.empty())
-      trace = "{\"traceEvents\":[";
-    else
+    if (compressed_trace_data_.empty()) {
+      trace = "{\"" +
+          std::string(base::trace_event::TracingAgent::kChromeTraceLabel) +
+          "\":[";
+    } else {
       trace = ",";
+    }
     trace += chunk_ptr->data();
     AddTraceChunkAndCompressOnFileThread(trace, false);
   }
@@ -269,23 +261,28 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
     if (!OpenZStreamOnFileThread())
       return;
 
-    if (compressed_trace_data_.empty())
-      AddTraceChunkAndCompressOnFileThread("{\"traceEvents\":[", false);
-
+    if (compressed_trace_data_.empty()) {
+      AddTraceChunkAndCompressOnFileThread(
+          "{\"" +
+          std::string(base::trace_event::TracingAgent::kChromeTraceLabel) +
+          "\":[",
+          false);
+    }
     AddTraceChunkAndCompressOnFileThread("]", false);
-    if (!system_trace_.empty()) {
+
+    for (auto const &it : GetAdditionalTracingAgentTrace()) {
       AddTraceChunkAndCompressOnFileThread(
-          ",\"systemTraceEvents\": " + system_trace_, false);
+          ",\"" + it.first + "\": " + it.second, false);
     }
+
     std::string metadataJSON;
     if (base::JSONWriter::Write(GetMetadata(), &metadataJSON) &&
         !metadataJSON.empty()) {
-      AddTraceChunkAndCompressOnFileThread(",\"metadata\": " + metadataJSON,
-                                           false);
-    }
-    if (!power_trace_.empty()) {
       AddTraceChunkAndCompressOnFileThread(
-          ",\"powerTraceAsString\": " + power_trace_, false);
+          ",\"" +
+          std::string(base::trace_event::TracingAgent::kMetadataTraceLabel) +
+          "\": " + metadataJSON,
+          false);
     }
     AddTraceChunkAndCompressOnFileThread("}", true);
 
@@ -301,14 +298,29 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
   scoped_ptr<z_stream> stream_;
   bool already_tried_open_;
   std::string compressed_trace_data_;
-  std::string system_trace_;
-  std::string power_trace_;
 
   DISALLOW_COPY_AND_ASSIGN(CompressedStringTraceDataSink);
 };
 
 }  // namespace
 
+TracingController::TraceDataSink::TraceDataSink() {}
+
+TracingController::TraceDataSink::~TraceDataSink() {}
+
+void TracingController::TraceDataSink::AddAgentTrace(
+    const std::string& trace_label,
+    const std::string& trace_data) {
+  DCHECK(additional_tracing_agent_trace_.find(trace_label) ==
+         additional_tracing_agent_trace_.end());
+  additional_tracing_agent_trace_[trace_label] = trace_data;
+}
+
+const std::map<std::string, std::string>&
+    TracingController::TraceDataSink::GetAdditionalTracingAgentTrace() const {
+  return additional_tracing_agent_trace_;
+}
+
 void TracingController::TraceDataSink::AddMetadata(
     const base::DictionaryValue& data) {
   metadata_.MergeDictionary(&data);