Add the ability for DevTools to wrap network transactions.

net/http/http_network_layer.cc

Index: net/http/http_network_layer.cc
diff --git a/net/http/http_network_layer.cc b/net/http/http_network_layer.cc
index 0704de420de32d29349e8e6d50f311387a362db3..dc49691514d4e360723b8d19a87724621fa74188 100644
--- a/net/http/http_network_layer.cc
+++ b/net/http/http_network_layer.cc
@@ -19,6 +19,8 @@
 
 namespace net {
 
+HttpNetworkLayer::TransactionFactory* g_network_transaction_factory_ = NULL;
+
 //-----------------------------------------------------------------------------
 HttpNetworkLayer::HttpNetworkLayer(HttpNetworkSession* session)
     : session_(session),
@@ -57,6 +59,12 @@ void HttpNetworkLayer::ForceAlternateProtocol() {
   HttpServerPropertiesImpl::ForceAlternateProtocol(pair);
 }
 
+// static
+void HttpNetworkLayer::SetTransactionFactory(
+    HttpNetworkLayer::TransactionFactory* factory) {
+  g_network_transaction_factory_ = factory;
+}
+
 //-----------------------------------------------------------------------------
 
 int HttpNetworkLayer::CreateTransaction(RequestPriority priority,
@@ -64,6 +72,10 @@ int HttpNetworkLayer::CreateTransaction(RequestPriority priority,
   if (suspended_)
     return ERR_NETWORK_IO_SUSPENDED;
 
+  if (g_network_transaction_factory_)
+    return g_network_transaction_factory_->CreateTransaction(
+        priority, GetSession(), trans);
+
   trans->reset(new HttpNetworkTransaction(priority, GetSession()));
   return OK;
 }