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

chrome/service/cloud_print/cloud_print_url_fetcher_unittest.cc

Index: chrome/service/cloud_print/cloud_print_url_fetcher_unittest.cc
diff --git a/chrome/service/cloud_print/cloud_print_url_fetcher_unittest.cc b/chrome/service/cloud_print/cloud_print_url_fetcher_unittest.cc
index 2507893ca2e6fd1c48c6b26a8464fd5b7b86b24a..8715496310d506dc91510ee574765f49be53e86e 100644
--- a/chrome/service/cloud_print/cloud_print_url_fetcher_unittest.cc
+++ b/chrome/service/cloud_print/cloud_print_url_fetcher_unittest.cc
@@ -62,7 +62,8 @@ class TestCloudPrintURLFetcher : public CloudPrintURLFetcher {
  public:
   explicit TestCloudPrintURLFetcher(
       base::MessageLoopProxy* io_message_loop_proxy)
-      : io_message_loop_proxy_(io_message_loop_proxy) {
+      : io_message_loop_proxy_(io_message_loop_proxy),
+        throttler_manager_(&throttler_delegate_){
   }
 
   virtual net::URLRequestContextGetter* GetRequestContextGetter() {
@@ -79,6 +80,8 @@ class TestCloudPrintURLFetcher : public CloudPrintURLFetcher {
 
   scoped_refptr<base::MessageLoopProxy> io_message_loop_proxy_;
 
+  TestURLRequestThrottlerManagerDelegate throttler_delegate_;
+
   // We set this as the throttler manager for the
   // TestURLRequestContext we create.
   net::URLRequestThrottlerManager throttler_manager_;