[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..2ecb8d26cb5ee5492504edd7075132995bbaa5f8 100644
--- a/content/browser/tracing/tracing_controller_impl_data_sinks.cc
+++ b/content/browser/tracing/tracing_controller_impl_data_sinks.cc
@@ -131,25 +131,26 @@ 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 (base::DictionaryValue::Iterator it(GetAdditionalTracingAgentTrace());
+         !it.IsAtEnd(); it.Advance()) {
+      std::string trace;
+      DCHECK(it.value().GetAsString(&trace));
+      if (it.key() == base::trace_event::TracingAgent::kCrOSTracingAgentName ||

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

Don't need to do this now but could probably go further in the future and not
have these if statements, just have the agent supply the key name.

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

Done.

+          it.key() == base::trace_event::TracingAgent::kETWTracingAgentName) {
+        AddTraceChunkAndPassToEndpoint(",\"systemTraceEvents\": " + trace);
+      } else if (it.key() ==
+                 base::trace_event::TracingAgent::kPowerTracingAgentName) {
+        AddTraceChunkAndPassToEndpoint(",\"powerTraceAsString\": " + trace);
+      }
+    }
+
     std::string metadataJSON;
     if (base::JSONWriter::Write(GetMetadata(), &metadataJSON) &&
         !metadataJSON.empty())
       AddTraceChunkAndPassToEndpoint(",\"metadata\": " + metadataJSON);
-    if (!power_trace_.empty()) {
-      AddTraceChunkAndPassToEndpoint(",\"powerTraceAsString\": " +
-                                     power_trace_);
-    }
 
     AddTraceChunkAndPassToEndpoint("}");
 
@@ -162,8 +163,6 @@ 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 +183,6 @@ 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,
@@ -273,20 +266,28 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
       AddTraceChunkAndCompressOnFileThread("{\"traceEvents\":[", false);
 
     AddTraceChunkAndCompressOnFileThread("]", false);
-    if (!system_trace_.empty()) {
-      AddTraceChunkAndCompressOnFileThread(
-          ",\"systemTraceEvents\": " + system_trace_, false);
+
+    for (base::DictionaryValue::Iterator it(GetAdditionalTracingAgentTrace());
+         !it.IsAtEnd(); it.Advance()) {
+      std::string trace;
+      DCHECK(it.value().GetAsString(&trace));
+      if (it.key() == base::trace_event::TracingAgent::kCrOSTracingAgentName ||
+          it.key() == base::trace_event::TracingAgent::kETWTracingAgentName) {
+        AddTraceChunkAndCompressOnFileThread(
+            ",\"systemTraceEvents\": " + trace, false);
+      } else if (it.key() ==
+                 base::trace_event::TracingAgent::kPowerTracingAgentName) {
+        AddTraceChunkAndCompressOnFileThread(
+            ",\"powerTraceAsString\": " + trace, 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);
-    }
     AddTraceChunkAndCompressOnFileThread("}", true);
 
     deflateEnd(stream_.get());
@@ -301,14 +302,23 @@ 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
 
+void TracingController::TraceDataSink::AddAdditionalTracingAgentTrace(
+    const std::string& agent_name,
+    const std::string& trace_data) {
+  additional_tracing_agent_trace_.SetString(agent_name, trace_data);
+}
+
+const base::DictionaryValue&
+    TracingController::TraceDataSink::GetAdditionalTracingAgentTrace() const {
+  return additional_tracing_agent_trace_;
+}
+
 void TracingController::TraceDataSink::AddMetadata(
     const base::DictionaryValue& data) {
   metadata_.MergeDictionary(&data);