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

net/url_request/url_request_throttler_simulation_unittest.cc

Index: net/url_request/url_request_throttler_simulation_unittest.cc
diff --git a/net/url_request/url_request_throttler_simulation_unittest.cc b/net/url_request/url_request_throttler_simulation_unittest.cc
index 256d343f45e20b0e9e5c94de8dbc9c931d1bc015..a3b8ce0e68f1d5231e956d98e8f9264b0c91a117 100644
--- a/net/url_request/url_request_throttler_simulation_unittest.cc
+++ b/net/url_request/url_request_throttler_simulation_unittest.cc
@@ -159,7 +159,7 @@ class Server : public DiscreteTimeSimulation::Actor {
     ++num_current_tick_queries_;
     if (!start_downtime_.is_null() &&
         start_downtime_ < now_ && now_ < end_downtime_) {
-      // TODO(joi): For the simulation measuring the increase in perceived
+      // For the simulation measuring the increase in perceived
       // downtime, it might be interesting to count separately the
       // queries seen by the server (assuming a front-end reverse proxy
       // is what actually serves up the 503s in this case) so that we could
@@ -285,12 +285,6 @@ class Server : public DiscreteTimeSimulation::Actor {
   DISALLOW_COPY_AND_ASSIGN(Server);
 };
 
-class TestingURLRequestThrottlerManager : public URLRequestThrottlerManager {
- public:
-  TestingURLRequestThrottlerManager() : URLRequestThrottlerManager() {
-  }
-};
-
 // Mock throttler entry used by Requester class.
 class MockURLRequestThrottlerEntry : public URLRequestThrottlerEntry {
  public:
@@ -427,7 +421,7 @@ class Requester : public DiscreteTimeSimulation::Actor {
 
     if (throttler_entry_->fake_now() - time_of_last_attempt_ >
         effective_delay) {
-      if (!throttler_entry_->ShouldRejectRequest(0)) {
+      if (!throttler_entry_->ShouldRejectRequest(NULL, 0)) {
         int status_code = server_->HandleRequest();
         MockURLRequestThrottlerHeaderAdapter response_headers(status_code);
         throttler_entry_->UpdateWithResponse("", &response_headers);
@@ -493,7 +487,7 @@ void SimulateAttack(Server* server,
   const size_t kNumAttackers = 50;
   const size_t kNumClients = 50;
   DiscreteTimeSimulation simulation;
-  TestingURLRequestThrottlerManager manager;
+  URLRequestThrottlerManager manager;
   ScopedVector<Requester> requesters;
   for (size_t i = 0; i < kNumAttackers; ++i) {
     // Use a tiny time_between_requests so the attackers will ping the
@@ -596,7 +590,7 @@ double SimulateDowntime(const TimeDelta& duration,
   Server server(std::numeric_limits<int>::max(), 1.0);
   server.SetDowntime(start_downtime, duration);
 
-  TestingURLRequestThrottlerManager manager;
+  URLRequestThrottlerManager manager;
   scoped_refptr<MockURLRequestThrottlerEntry> throttler_entry(
       new MockURLRequestThrottlerEntry(&manager));
   if (!enable_throttling)