HPACK optimal Huffman code instrumentation and UMA collection.

net/http/http_network_transaction.cc

Index: net/http/http_network_transaction.cc
diff --git a/net/http/http_network_transaction.cc b/net/http/http_network_transaction.cc
index 36deb99def16fb9ce674afb4b20109cc2fb7c75a..c4d17abaf2fa2b079cf3b22f6c63dfc8ec1d71d4 100644
--- a/net/http/http_network_transaction.cc
+++ b/net/http/http_network_transaction.cc
@@ -54,6 +54,7 @@
 #include "net/socket/ssl_client_socket.h"
 #include "net/socket/ssl_client_socket_pool.h"
 #include "net/socket/transport_client_socket_pool.h"
+#include "net/spdy/hpack_huffman_aggregator.h"
 #include "net/spdy/spdy_http_stream.h"
 #include "net/spdy/spdy_session.h"
 #include "net/spdy/spdy_session_pool.h"
@@ -1100,6 +1101,14 @@ int HttpNetworkTransaction::DoReadHeadersComplete(int result) {
     stream_->GetSSLInfo(&response_.ssl_info);
 
   headers_valid_ = true;
+
+  if (session_->huffman_aggregator()) {
+    session_->huffman_aggregator()->AggregateTransactionCharacterCounts(
+        *request_,
+        request_headers_,
+        proxy_info_.proxy_server(),
+        *response_.headers);
+  }
   return OK;
 }