[net/http auth] Split HttpAuthHandler creation from initialization.

net/http/http_auth_cache_unittest.cc

Index: net/http/http_auth_cache_unittest.cc
diff --git a/net/http/http_auth_cache_unittest.cc b/net/http/http_auth_cache_unittest.cc
index 1b8a5c89fb802129182742a44ee1d486a6a07231..036c6e3ffe04e665b4bf839b22bb3b30553023c9 100644
--- a/net/http/http_auth_cache_unittest.cc
+++ b/net/http/http_auth_cache_unittest.cc
@@ -23,9 +23,9 @@ class MockAuthHandler : public HttpAuthHandler {
  public:
   MockAuthHandler(const std::string& scheme,
                   const std::string& realm,
-                  HttpAuth::Target target) {
+                  HttpAuth::Target target)
+      : HttpAuthHandler(scheme) {
     // Can't use initializer list since these are members of the base class.
-    auth_scheme_ = scheme;
     realm_ = realm;
     target_ = target;
   }