Add the ability for DevTools to wrap network transactions.

net/http/http_cache.cc

Index: net/http/http_cache.cc
diff --git a/net/http/http_cache.cc b/net/http/http_cache.cc
index 8c7dc1e6fbf312c99d17e8d431990fd6af224344..01150a4b5c19d0d628e4c5b8b1c9f78e792f2777 100644
--- a/net/http/http_cache.cc
+++ b/net/http/http_cache.cc
@@ -291,12 +291,8 @@ HttpCache::HttpCache(const net::HttpNetworkSession::Params& params,
       backend_factory_(backend_factory),
       building_backend_(false),
       mode_(NORMAL),
-      quic_server_info_factory_(params.enable_quic_persist_server_info ?
-          new QuicServerInfoFactoryAdaptor(this) : NULL),
       network_layer_(new HttpNetworkLayer(new HttpNetworkSession(params))) {
-  HttpNetworkSession* session = network_layer_->GetSession();
-  session->quic_stream_factory()->set_quic_server_info_factory(
-      quic_server_info_factory_.get());
+  SetupQuicServerInfoFactory(network_layer_->GetSession());
 }
 
 
@@ -319,6 +315,7 @@ HttpCache::HttpCache(HttpTransactionFactory* network_layer,
       building_backend_(false),
       mode_(NORMAL),
       network_layer_(network_layer) {
+  SetupQuicServerInfoFactory(network_layer_->GetSession());
 }
 
 HttpCache::~HttpCache() {
@@ -1000,6 +997,16 @@ bool HttpCache::RemovePendingTransactionFromPendingOp(PendingOp* pending_op,
   return false;
 }
 
+void HttpCache::SetupQuicServerInfoFactory(HttpNetworkSession* session) {
+  if (session->params().enable_quic_persist_server_info &&
+      !session->quic_stream_factory()->has_quic_server_info_factory()) {
+    DCHECK(!quic_server_info_factory_);
+    quic_server_info_factory_.reset(new QuicServerInfoFactoryAdaptor(this));
+    session->quic_stream_factory()->set_quic_server_info_factory(
+        quic_server_info_factory_.get());
+  }
+}
+
 void HttpCache::ProcessPendingQueue(ActiveEntry* entry) {
   // Multiple readers may finish with an entry at once, so we want to batch up
   // calls to OnProcessPendingQueue.  This flag also tells us that we should