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

net/url_request/url_request_test_util.h

Index: net/url_request/url_request_test_util.h
diff --git a/net/url_request/url_request_test_util.h b/net/url_request/url_request_test_util.h
index 26ce942f73d008357f48a7643e8945a8a71e044c..14dd1277929d7500b5a195b09ea3baffd20fe205 100644
--- a/net/url_request/url_request_test_util.h
+++ b/net/url_request/url_request_test_util.h
@@ -38,6 +38,7 @@
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "net/url_request/url_request_context_storage.h"
+#include "net/url_request/url_request_throttler_manager.h"
 
 using base::TimeDelta;
 
@@ -101,6 +102,14 @@ class TestURLRequest : public net::URLRequest {
   const scoped_ptr<net::URLRequestContext> context_;
 };
 
+
+// An URLRequestThrottlerManagerDelegate that always allows rejecting requests.
+class TestURLRequestThrottlerManagerDelegate
+    : public net::URLRequestThrottlerManagerDelegate {
+ public:
+  virtual bool MayRejectRequest(net::URLRequest* request) OVERRIDE;
+};
+
 //-----------------------------------------------------------------------------
 
 class TestDelegate : public net::URLRequest::Delegate {