Introduce a delegate to avoid hardcoding "chrome-extension" in net/.

net/url_request/url_request_test_util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/url_request/url_request_test_util.h"
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/threading/thread.h"
@@ skipping 475 matching lines @@
   }
 
   return allow;
 }
 
 bool TestNetworkDelegate::OnCanAccessFile(const net::URLRequest& request,
                                           const FilePath& path) const {
   return true;
 }
 
+bool TestNetworkDelegate::OnCanThrottleRequest(
+    const net::URLRequest& request) const {
+  return true;
+}
+
 // static
 std::string ScopedCustomUrlRequestTestHttpHost::value_("127.0.0.1");
 
 ScopedCustomUrlRequestTestHttpHost::ScopedCustomUrlRequestTestHttpHost(
   const std::string& new_value)
     : old_value_(value_),
       new_value_(new_value) {
   value_ = new_value_;
 }
 
 ScopedCustomUrlRequestTestHttpHost::~ScopedCustomUrlRequestTestHttpHost() {
   DCHECK_EQ(value_, new_value_);
   value_ = old_value_;
 }
 
 // static
 const std::string& ScopedCustomUrlRequestTestHttpHost::value() {
   return value_;
 }