Adding instrumentation to locate the source of jankiness.

net/http/http_stream_parser.cc

Index: net/http/http_stream_parser.cc
diff --git a/net/http/http_stream_parser.cc b/net/http/http_stream_parser.cc
index 4a60a6bd40e949f9ea67c52fcef2affc8fbb1590..4c1041b537613cf562eb2ca04b752c1ee6ac4ded 100644
--- a/net/http/http_stream_parser.cc
+++ b/net/http/http_stream_parser.cc
@@ -368,6 +368,11 @@ void HttpStreamParser::OnIOComplete(int result) {
   // The client callback can do anything, including destroying this class,
   // so any pending callback must be issued after everything else is done.
   if (result != ERR_IO_PENDING && !callback_.is_null()) {
+    // TODO(vadimt): Remove ScopedProfile below once crbug.com/424359 is fixed.
+    tracked_objects::ScopedProfile tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION(
+            "424359 HttpStreamParser::OnIOComplete callback"));
+
     CompletionCallback c = callback_;
     callback_.Reset();
     c.Run(result);
@@ -375,6 +380,10 @@ void HttpStreamParser::OnIOComplete(int result) {
 }
 
 int HttpStreamParser::DoLoop(int result) {
+  // TODO(vadimt): Remove ScopedProfile below once crbug.com/424359 is fixed.
+  tracked_objects::ScopedProfile tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION("424359 HttpStreamParser::DoLoop"));
+
   do {
     DCHECK_NE(ERR_IO_PENDING, result);
     DCHECK_NE(STATE_DONE, io_state_);