Slow Reports - Embed Metadata in Traces

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 a6d6e37ad1398a4df0772058d9f76cbd2bfa6eef..6bdcafb0bdfdcf636ac0f6fd39e49e855cc60295 100644
--- a/content/browser/tracing/tracing_controller_impl_data_sinks.cc
+++ b/content/browser/tracing/tracing_controller_impl_data_sinks.cc
@@ -128,11 +128,17 @@ class StringTraceDataSink : public TracingController::TraceDataSink {
     system_trace_ = data;
   }
 
+  void SetMetadata(const std::string& data) override {
+    metadata_ = data;
+  }
+
   void Close() override {
     AddTraceChunkAndPassToEndpoint("]");
     if (!system_trace_.empty())
       AddTraceChunkAndPassToEndpoint(",\"systemTraceEvents\": " +
                                      system_trace_);
+    if (!metadata_.empty())
+      AddTraceChunkAndPassToEndpoint(",\"metadata\": " + metadata_);
     AddTraceChunkAndPassToEndpoint("}");
 
     endpoint_->ReceiveTraceFinalContents(trace_);
@@ -144,6 +150,7 @@ class StringTraceDataSink : public TracingController::TraceDataSink {
   scoped_refptr<TracingController::TraceDataEndpoint> endpoint_;
   std::string trace_;
   std::string system_trace_;
+  std::string metadata_;
 
   DISALLOW_COPY_AND_ASSIGN(StringTraceDataSink);
 };
@@ -168,6 +175,10 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
     system_trace_ = data;
   }
 
+  void SetMetadata(const std::string& data) override {
+    metadata_ = data;
+  }
+
   void Close() override {
     BrowserThread::PostTask(
         BrowserThread::FILE, FROM_HERE,
@@ -255,6 +266,10 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
       AddTraceChunkAndCompressOnFileThread(
           ",\"systemTraceEvents\": " + system_trace_, false);
     }
+    if (!metadata_.empty()) {
+      AddTraceChunkAndCompressOnFileThread(",\"metadata\": " + metadata_,
+                                           false);
+    }
     AddTraceChunkAndCompressOnFileThread("}", true);
 
     deflateEnd(stream_.get());
@@ -268,6 +283,7 @@ class CompressedStringTraceDataSink : public TracingController::TraceDataSink {
   bool already_tried_open_;
   std::string compressed_trace_data_;
   std::string system_trace_;
+  std::string metadata_;
 
   DISALLOW_COPY_AND_ASSIGN(CompressedStringTraceDataSink);
 };