Set up field trials for SSL read/write buffer sizes.

net/url_request/url_request_http_job.cc

Index: net/url_request/url_request_http_job.cc
diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc
index aa8ca6670ba7196a3106638517aecab657d42f82..d7eca2f840a5b77df7dc9dcd92673c419dbda987 100644
--- a/net/url_request/url_request_http_job.cc
+++ b/net/url_request/url_request_http_job.cc
@@ -1515,6 +1515,10 @@ void URLRequestHttpJob::RecordTimer() {
   request_creation_time_ = base::Time();
 
   UMA_HISTOGRAM_MEDIUM_TIMES("Net.HttpTimeToFirstByte", to_start);
+  if (request_info_.upload_data_stream &&
+      request_info_.upload_data_stream->size() > 1024 * 1024) {
+    UMA_HISTOGRAM_MEDIUM_TIMES("Net.HttpTimeToFirstByte.LargeUpload", to_start);
+  }
 }
 
 void URLRequestHttpJob::ResetTimer() {